lark about vs romp

lark about is not a noun while romp is a noun.

Word	Noun	Adjective	Verb	Adverb
lark about	No	No	Yes	No
romp	Yes	No	Yes	No

As verbs, lark about and romp are synonyms defined as:

Other synonyms of lark about include cavort, disport, frisk, frolic, gambol, lark, rollick, run around, skylark, sport.

lark about (noun)	romp (noun)
	gay or light-hearted recreational activity for diversion or amusement
	an easy victory
	a girl who behaves in a boyish manner