A
Japanese adjective meaning "beautiful".
It's used commonly by anime fans as part of their
broken repertoire of Japanese words. Most of the
time it's not even used in the right context, betraying the speaker's ignorance and unwillingness to actually learn the meaning of the Japanese terms they are obsessed over.
Female weebs are distinguished by their frequent use of the term. It's not used by male weebs very often.
Weeb: this game is so kawaii (referring to halo 5)
Me: Shut the fuck up you dumbass. Kawaii means beautiful, not
amazing.
Weeb 2: ur so kawaii >.<
Me: I'm a straight guy,
don't tell me that I'm
fucking "beautiful".