Where does “hūmidus” come from?

hūmidus (Latin) comes from Latin umidus, from Latin -idus, from Proto-Italic *-iðos.

Ancestry of “hūmidus”, step by step

Step	Language	Word	Meaning
1	Latin	umidus	moist, humid, damp, dank, wet; formerly liquid,...
2	Latin	-idus	tending to
3	Proto-Italic	*-iðos	—

hūmidus — Etymology, Origin & Word History | Etymology Explorer