boss character; boss enemy
Video game term for a powerful enemy, typically encountered at the end of a stage or level.
See also: ボス
The boss character in this game is very hard to defeat.
I gather items in preparation for the next stage's boss.
Variant with interpunct; less common but sometimes seen.
Wasei-eigo (Japanese-made English) combining ボス (boss) and キャラ (character, abbreviation of キャラクター).