let alone vs refrain

let alone is not a noun while refrain is a noun.

Word	Noun	Adjective	Verb	Adverb
let alone	No	No	Yes	Yes
refrain	Yes	No	Yes	No

As verbs, refrain is a hypernym of let alone; that is, refrain is a word with a broader meaning than let alone:

Other hypernyms of let alone include forbear.

let alone (noun)	refrain (noun)
	the part of a song where a soloist is joined by a group of singers

let alone (verb)	refrain (verb)
leave unchanged or undisturbed or refrain from taking	choose not to consume
	resist doing something

let alone (adverb)	refrain (adverb)
much less