hole / opening, aperture / pit / cave, cavern / lair, den, burrow / loss, deficit / flaw, defect

to enter, go into, get into a place or a thing / to join a group or organization / to be contained (in), to be included (in) / to be a member of a group, set, category

loser, (a social) failure, also-ran

failed creation; failure

(colloquial) current boyfriend

everything

(slang) Alternative form of 彼氏 (kareshi, “boyfriend”)

everyone, one and all

a common rabbit

peephole (hole in a door through which to look)