“latch” – English explanatory dictionary

noun the fastening for a door consisting of a small bar which fits into a catch ○ The burglars pushed on the door and broke the latch. Synonym fastener □ the door is on the latch the door is held shut by a latch but is not locked ○ Leave the door on the latch – I’ll be back in a minute. ■ verb 1. to close with a latch ○ It’s not enough just to latch the door, it must be locked at night. 2. □ to latch on to something to understand something or to take up something (informal.) ○ Children latch on to their parents’ bad habits very quickly. ○ The reporters quickly latched on to the fact that the Prime Minister did not applaud the Chancellor’s speech.

(lach), v. t. [Cf. F. lecher to lick (of German origin). Cf. Lick.] To smear; to anoint. [Obs.] Shak.

n. [OE. lacche, fr. lacchen to seize, As. laeccan.]
1. That which fastens or holds; a lace; a snare. [Obs.] Rom. of R.
2. A movable piece which holds anything in place by entering a notch or cavity; specifically, the catch which holds a door or gate when closed, though it be not bolted.
3. (Naut.) A latching.
4. A crossbow. [Obs.] Wright.

v. t. [imp. & p. p. Latched (lacht); p. pr. & vb. n. Latching.] [OE. lacchen. See Latch. n.]
1. To catch so as to hold. [Obs.] “Those that remained threw darts at our men, and latching our darts, sent them again at us.” Golding.
2. To catch or fasten by means of a latch. “The door was only latched.” Locke.