Latch

[lach] /lætʃ/

noun
1.
a device for holding a door, gate, or the like, closed, consisting basically of a bar falling or sliding into a catch, groove, hole, etc.
verb (used with object)
2.
to close or fasten with a latch.
verb (used without object)
3.
to close tightly so that the latch is secured:
The door won’t latch.
Verb phrases
4.
latch on,

5.
latch onto, Informal.

/lætʃ/
noun
1.
a fastening for a gate or door that consists of a bar that may be slid or lowered into a groove, hole, etc
2.
a spring-loaded door lock that can be opened by a key from outside
3.
(electronics) Also called latch circuit. a logic circuit that transfers the input states to the output states when signalled, the output thereafter remaining insensitive to changes in input status until signalled again
verb
4.
to fasten, fit, or be fitted with or as if with a latch
v.

Old English læccan “to grasp or seize,” from Proto-Germanic *lakkijanan. Not found in other Germanic languages; probably from PIE *(s)lagw- “to seize” (see analemma). In its original sense the verb was paralleled in Middle English and then replaced by French import catch (v.). Meaning “to fasten with a latch” is mid-15c. Related: Latched; latching.
n.

a fastening for a door, etc., late 13c., probably from latch (v.).

A digital logic circuit used to store one or more bits. A latch has a data input, a clock input and an output. When the clock input is active, data on the input is “latched” or stored and transfered to the output either immediately or when the clock input goes inactive. The output will then retain its value until the clock goes active again.
See also flip-flop.
(1995-02-03)