latch on vs cotton on

latch on and cotton on both are verbs.

Word	Noun	Adjective	Verb	Adverb
latch on	No	No	Yes	No
cotton on	No	No	Yes	No

As verbs, latch on and cotton on are synonyms defined as:

latch on and cotton on: understand, usually after some initial difficulty

Other synonyms of latch on include catch on, get it, get onto, get wise, tumble, twig.

latch on (verb)	cotton on (verb)
understand, usually after some initial difficulty	understand, usually after some initial difficulty
adopt
take hold of or attach to