chirk up vs lighten

chirk up and lighten both are verbs.

Word	Noun	Adjective	Verb	Adverb
chirk up	No	No	Yes	No
lighten	No	No	Yes	No

As verbs, lighten is a hyponym of chirk up; that is, lighten is a word with a more specific, narrower meaning than chirk up:

Other hyponyms of chirk up include exuberate, exult, jubilate, rejoice, triumph, buoy up, lighten up.

chirk up (verb)	lighten (verb)
become cheerful	make more cheerful through the use of color
	become lighter
	alleviate or remove (pressure or stress) or make less oppressive
	become more cheerful
	reduce the weight on; make lighter
	make more cheerful