come vs plump in

come is a noun but plump in is not a noun.

Word	Noun	Adjective	Verb	Adverb
come	Yes	No	Yes	No
plump in	No	No	Yes	No

As verbs, plump in is a hyponym of come; that is, plump in is a word with a more specific, narrower meaning than come:

come (noun)	plump in (noun)
the thick white fluid containing spermatozoa that is ejaculated by the male genital tract

come (verb)	plump in (verb)
come to pass; arrive, as in due course	arrive suddenly and unannounced
be found or available
reach or enter a state, relation, condition, use, or position
happen as a result
have a certain priority
come to one's mind; suggest itself
move toward, travel toward something or somebody or approach something or somebody
be received
cover a certain distance
reach a destination; arrive by movement or progress
experience orgasm
come under, be classified or included
proceed or get along
extend or reach
to be the product or result
exist or occur in a certain point in a series
be a native of
to measure up to in kind or quality
add up in number or quantity
come forth
come from; be connected by a relationship of blood, for example