mix in vs meld

mix in is not a noun while meld is a noun.

Word	Noun	Adjective	Verb	Adverb
mix in	No	No	Yes	No
meld	Yes	No	Yes	No

As verbs, meld is a hypernym of mix in; that is, meld is a word with a broader meaning than mix in:

Other hypernyms of mix in include blend, coalesce, combine, commingle, conflate, flux, fuse, immix, merge, mix.

mix in (noun)	meld (noun)
	a form of rummy using two decks of cards and four jokers; jokers and deuces are wild; the object is to form groups of the same rank

mix in (verb)	meld (verb)
cause (something) to be mixed with (something else)	mix together different elements
add as an additional element or part	lose its distinct outline or shape; blend gradually
	announce for a score; of cards in a card game