from the Japanese verb 'ukeru' (receive) it's used in anime/manga and fanfiction for the "bottom" or "passive" in a wordyaoi/word/wordshounen-ai/word (male/male) relationship.
Generally the shorter, cuter, sweeter of the two... generally.
See wordseme/word for more info.

during a guy x guy relationship the older male is the seme and the younger is the UKE meaning the younger is the female part in the relationship.

Alternative word to describe a Martial Arts partner, or attacker, who is the recipient of the technique to be practiced or attempted.

Also, can be the problem child from the class, i.e. doubting Thomas, to be used for an example to train them mentally. The Demonstratee.

Northern English Slang - Ukelele a stringed musical instrument popularised in the 1930's by the comedian George Formby

A shortening for the word Ukrainian. Used in reference to a person of Ukrainian background.

The male in a yaoi relationship that's usually the bottom, and recieves it instead of giving it.
Rei Ryugazaki.

A person with an absolute massive dong that will not simp if their life depends on it