關門

to close a door / to lock a door / (of a shop etc) to close (for the night, or permanently)

mountain pass / to close; to shut; to turn off / to confine; to lock (sb) up; to shut (sb in a room, a bird in a cage etc) / to concern; to involve

gate / door / CL:扇[shan4] / gateway / doorway / CL:個|个[ge4] / opening / valve / switch / way to do something / knack / family / house / (religious) sect / school (of thought) / class / category / phylum or division (taxonomy) / classifier for large guns / classifier for lessons, subjects, branches of technology / (suffix) -gate (i.e. scandal; derived from Watergate)

to close down a business for good and put the best face on it (idiom)

to catch a thief by closing his escape route (idiom)

last disciple of a master

lit. shut the door and beat the dog (idiom) / fig. seal off the enemy's avenue of retreat, then strike hard