Prince, from the Latin root princeps, is a general term for a monarch, for a member of a monarch's or former monarch's family, and is a hereditary title in some members of Europe's highest nobility. The female equivalent is a princess.
Emperor Augustus established the formal position of monarch on the basis of principate, not dominion. He also tasked his grandsons as summer rulers of the city when most of the government were on holiday in the country or attending religious rituals, and, for that task, granted them the title of princeps.
The title has generic and substantive meanings:
As a title, by the end of the medieval era, prince was borne by rulers of territories that were either substantially smaller than or exercised fewer of the rights of sovereignty than did emperors and kings. A lord of even a quite small territory might come to be referred to as a prince before the 13th century, either from translations of a native title into the Latin princeps (as for the hereditary ruler of Wales), or when the lord's territory was allodial. The lord of an allodium owned his lands and exercised prerogatives over the subjects in his territory absolutely, owing no feudal homage or duty as a vassal to a liege lord, nor being subject to any higher jurisdiction. Most small territories designated as principalities during feudal eras were allodial, e.g. the Princedom of Dombes.
Lords who exercised lawful authority over territories and people within a feudal hierarchy were also sometimes regarded as princes in the general sense, especially if they held the rank of count or higher. This is attested in some surviving styles for e.g., British earls, marquesses, and dukes are still addressed by the Crown on ceremonial occasions as high and noble princes (cf. Royal and noble styles).
In parts of the Holy Roman Empire in which primogeniture did not prevail (i.e. Germany), all legitimate agnates had an equal right to the family's hereditary titles. While this meant that offices, such as emperor, king, and elector could only be legally occupied by one dynast at a time, holders of such other titles as duke, margrave, landgrave, count palatine, and prince could only differentiate themselves by adding the name of their appanage to the family's original title. Not only did this tend to proliferate unwieldy titles (e.g. Princess Katherine of Anhalt-Zerbst ane Karl, Count Palatine of Zweibrucken-Neukastell-Kleeburg), but as agnatic primogeniture gradually became the norm in the Holy Roman Empire by the end of the eighteenth century, another means of distinguishing the monarch from other members of his dynasty became necessary. Gradual substitution of the title of Prinz for the monarch's title of Fürst occurred, and became customary in all German dynasties except in the grand duchies of Mecklenburg and Oldenburg. Both Prinz and Fürst are translated into English as "prince", but they reflect not only different but mutually exclusive terms.
This distinction had evolved before the eighteenth century (in most families: Liechtenstein long remained an exception, cadets and females using Fürst/Fürstin into the 19th century) for dynasties headed by a Fürst in Germany. The custom spread through the Continent to such an extent that a renowned imperial general who belonged to a cadet branch of a reigning ducal family, remains best known to history by the generic dynastic title, Prince Eugene of Savoy. Note that the princely title was used as a prefix to his Christian name, which also became customary.
Cadets of France's princes étrangers began to affect similar usage but when, for example, the House of La Tour d'Auvergne's ruling dukes of Bouillon, attempted to use the same style, it was initially resisted by historians such as Père Anselme -- who, however, willingly recognized use of territorial titles, i.e. he accepts that the ducal heir apparent is known as prince de Bouillon, but would record in 1728 only that the heir's cousin, the comte d'Oliergues was "known as the Prince Frederick" ("dit le prince Frédéric").
The post-medieval rank of gefürsteter Graf (princely count) embraced but elevated the German equivalent of the intermediate French, English and Spanish nobles. In Germany, these nobles rose to dynastic status by preserving from the Imperial crown (de jure after the Peace of Westphalia in 1648) the exercise of such sovereign prerogatives as the minting of money; the muster of military troops and the right to wage war and contract treaties; local judicial authority and constabular enforcement; and the habit of inter-marrying with sovereign dynasties. Eventually, these titles came to be more highly valued than that of Fürst itself, and by the 19th century, their cadets would become known as Prinzen.
The husband of a queen regnant is usually nowadays titled prince or prince consort, whereas the wives of male monarchs take the female equivalent of their husbands' title -- the same as is used when a female mounts the throne in her own right, such as empress or queen. In Brazil, Spain and Portugal, however, the husband of a female monarch was accorded the masculine equivalent of her title -- at least after she bore him a child. In previous epochs, husbands of queens regnant often shared their consorts' regnal title and rank.
But in cultures which allow the ruler to have several wives (e.g. four in Islam) and/or official concubines, for these women sometimes collectively referred to as harem there are often specific rules determining their hierarchy and a variety of titles, which may distinguish between those whose offspring can be in line for the succeesion or not, or specifically who is mother to the heir to the throne.
To complicate matters, the style His Royal Highness, a prefix normally accompanying the title of a dynastic prince, of royal or imperial rank, that is, can be awarded separately (as a compromise or consolation prize, in some sense).
Some princely titles are derived from that of national rulers, such as tsarevich from tsar. Other examples are (e)mirza(da), khanzada, nawabzada, sahibzada, shahzada, sultanzada (all using the Persian patronymic suffix -zada, meaning son, descendant.
However, some princely titles develop in unusual ways, such as adoption of a style for dynasts which is not pegged to the ruler's title, but rather continues an old tradition (e.g. grand duke in Romanov Russia), claims dynastic succession to a lost monarchy (e.g. prince de Tarente for the La Trémoïlle heirs to the Neapolitan throne, or is simply assumed by fiat (e.g. prince Français by the House of Bonaparte).
In some dynasties, a specific style other than prince has become customary for dynasts, such as fils de France in the House of Capet, and infante in Spain, Portugal, and Brazil (infante was borne by children of the monarch other than the heir apparent, for whom each realm did use a unique princely title, viz, "Prince Imperial" in Brazil, "Prince of Brazil" in Portugal until 1822, and "Prince of Asturias" in Spain).
European dynasties usually awarded apanages to princes of the blood, typically attached to a feudal noble title, such as Britain's royal dukes , the Dauphin in France, the Count of Flanders in Belgium, and the Count of Syracuse in Sicily. Sometimes appanage titles were princely, e.g. Prince of Achaia (Courtenay), prince de Condé (Bourbon), Prince of Carignan (Savoy), but it was the fact that their owners were of princely rank rather than that they held a princely title which ensured their prominence.
Though these offices must not be reserved for members of the ruling dynasty, in some traditions they are, possibly even reflected in the style of the office, e.g. prince-lieutenant in Luxembourg repeatedly filled by the Crown prince before the grand duke's abdication, or in form of consortium imperii.
Some monarchies even have a practice in which the Monarch can formally abdicate in favor of his heir, and yet retain a kingly title with executive power, e.g. Maha Upayuvaraja (Sanskrit for Great Joint King in Cambodia), though sometimes also conferred on powerful regents who exercised executive powers.
One type of prince belongs in both the genealogical royalty and the territorial princely styles. A number of nobiliary territories, carrying with them the formal style of prince, are not or no longer actual political, administrative, principalities, but are maintained as essentially honorary titles and are awarded traditionally (or occasionally) to princes of the blood, as an appanage.
This is done in particular for the heir to the throne, creating a de facto primogeniture, who is often awarded a particular principality in each generation, so that it becomes synonymous with the first in line for the throne, even if there is no automatic legal mechanism to do so.
Examples of such titles are:
In several countries of the European continent, e.g. in France, prince can be an aristocratic title of someone having a high rank of nobility in chief of a geographical place, but no actual territory and without any necessary link to the royal family, which makes comparing it with e.g. the British system of royal princes difficult.
The kings of France started to bestow the style of prince, as a title among the nobility, from the 16th century onwards. These titles were created by elevating a seigneurie to the nominal status of a principality -- although prerogatives of sovereignty were never conceded in the letters patent. These titles held no official place in the hierarchy of the nobility, but were often treated as ranking just below dukedoms, since they were often inherited (or assumed) by ducal heirs:
This can even occur in a monarchy within which an identical but real and substantive feudal title exists, such as Fürst in German. An example of this is:
Spain and France
In other cases, such titular princedoms are created in chief of an event, such as a treaty of a victory. An example of this is:
Poland and Russia
In Poland specifically, the titles of prince dated either to the times before the Union of Lublin or were granted to Polish nobles by foreign kings, as the law in Poland forbade the king from dividing nobility by granting them hereditary titles. For more information, see The Princely Houses of Poland.
In the Russian system, knyaz, translated as "prince", is the highest degree of official nobility. Members of older dynasties that were eventually subjected to the Russian imperial dynasty were also accorded the title of knyaz -- sometimes after first being allowed to use the higher title of tsarevich (e.g. the Princes Gruzinsky and Sibirsky. Rurikid branches used the knyaz title also after they were succeeded by the Romanovs as the Russian imperial dynasty. An example of this is:
In each case, the title is followed (when available) by the female form and then (not always available, and obviously rarely applicable to a prince of the blood without a principality) the name of the territorial associated with it, each separated by a slash. If a second title (or set) is also given, then that one is for a Prince of the blood, the first for a principality. Be aware that the absence of a separate title for a prince of the blood may not always mean no such title exists; alternatively, the existence of a word does not imply there is also a reality in the linguistic territory concerned; it may very well be used exclusively to render titles in other languages, regardless whether there is a historical link with any (which often means that linguistic tradition is adopted)
Etymologically, we can discern the following traditions (some languages followed a historical link, e.g. within the Holy Roman Empire, not their linguistic family; some even fail to follow the same logic for certain other aristocratic titles):
Applying these essentially western concepts, and terminology, to other cultures even when they don't do so, is common but in many respects rather dubious. Different (historical, religious...) backgrounds have also begot significantly different dynastic and nobiliary systems, which are poorly represented by the 'closest' western analogy.
It therefore makes sense to treat these per civilization.
In ancient China, the title of prince developed from being the highest title of nobility (synonymous with duke) in the Zhou Dynasty, to five grades of princes (not counting the sons and grandsons of the emperor) by the time of the fall of the Qing Dynasty.The Chinese word for prince 'Wang' 王 literally means King as Chinese believe the emperor 'huangdi'皇帝 is the ruler of all kings. The most accurate translation of the English word 'prince' in Chinese is 皇子（son of the Emperor) or 王子 (son of the King).
In Japan, the title of prince (kôshaku 公爵) was used as the highest title of kazoku (華族 Japanese modern nobility) before the present constitution. The title kôshaku, however, is more commonly translated as duke to avoid confusion with the royal ranks in the imperial household, shinnô (親王 literally king of the blood), female naishinnô (内親王 literally queen (by herself) of the blood), and shinnôhi 親王妃 literally consort of king of the blood), or ô (王 literally king); female, jyo-ôh (女王 literally queen (by herself)) and ôhi (王妃 literally consort of king). The former is the higher title of a male member of the Imperial family and the latter is the lower.
In states with an element of theocracy, this can affect princehood in several ways, such as the style of the ruler (e.g. with a secondary title meaning son or servant of a named divinity), but also the mode of succession (even reincarnation and recognition).
Furthermore, certain religious offices may be considered of princely rank, and/or imply comparable temporal rights.
See Prince of the Church for the main Christian versions. Also in Christianity, Jesus Christ is sometimes referred to as the Prince of Peace. Other likely titles for Jesus Christ are Prince of Princes and Prince of the Covenant. Further, Satan is often titled the Prince of Darkness; and in the Christian faith he is also referred to as the Prince of this World and the Prince of the Power of the Air. Another title for Satan, not as common today but apparently so in approximately 30 A.D. by the Pharisees of the day, was the title Prince of the Devils.