決め込む， 決めこむ， 決込む， 極め込む， きめこむ
1. to take for granted, to assume, to be convinced (that), to jump to the conclusion (that)
2. to pretend (to be), to pose (as), to fancy oneself (to be), to feign (e.g. ignorance)
3. to go through with (what one decided to do), to persist in doing, ...
tbd