A houpeland (or houpellande, or any of several other variant spellings) is basically a huge dress (full circle starting at the shoulders) with very big drapey sleeves. It is normally worn belted, and often has a high neckline.
It was worn as the outermost of the normal three layers (over chemise, then cotehardie).
For men, its length could be anywhere between the backside and the ground, while for women it was commonly groundlength or longer.
One school of thought beleives it to be a predecessor to the Burgundian, by the front being left unhooked or buttoned, and then 'mutated' further into the true Burgundian style. (Italian Renaissance garb is thought to have an entirely different lineage.)
What is this? This is The Garbindex - a guide to making garb for recreationists (ie how to sew clothes that will make you look genuinely medieval, when 'playing' with such groups as the SCA, doing LARP - or even making something really genuine for drama.)
Use these resources to find resources that will help you create clothing that looks great - and real!