1 a small metal bar that is used for fastening a door or a gate. You have to lift the latch in order to open the door. 门闩
2 a type of lock for a door that you open with a key from the outside 碰锁
latch²
/lætʃ ||; lætʃ/verblatch on (to sth)(informal 非正式) to understand sth 明白；理解: It took them a while to latch on to what she was talking about.他们想了一会儿才明白她说的是什么意思。