Very small of its kind.
[English miniature, reinforced by minimum.]
Mini- has been in demand throughout the twentieth century but especially so since the 1960s as a result of names given to fashionable items of the time, especially minicars and then miniskirts. Since then, many terms have appeared, as it is often added to nouns to indicate something fashionably or notably small. A few examples are minibar (a selection of alcoholic drinks in a hotel room), mini-break (a short holiday of a few days), minibus, minicam (a miniaturized camera), minimart, miniseries, and minivan.
It is also now commonly a word in its own right, as in mini rugby and the British mini roundabout, and as an abbreviation for miniskirt, minicar (particularly as a tradename, Mini), and minicomputer, a computer of medium power, more than a microcomputer but less than a mainframe.