开口

to open one's mouth / to start to talk

to open / to start / to turn on / to boil / to write out (a prescription, check, invoice etc) / to operate (a vehicle) / carat (gold) / abbr. for Kelvin, 開爾文|开尔文[Kai1 er3 wen2] / abbr. for 開本|开本[kai1 ben3], book format

mouth / classifier for things with mouths (people, domestic animals, cannons, wells etc) / classifier for bites or mouthfuls

(Internet slang) to use foul language (pun on 出口成章[chu1 kou3 cheng2 zhang1])

a dike breaks / fig. to provide facilities (for evil deeds) / to open the floodgates