Where does “trepido” come from?

trepido (Latin) comes from Latin trepidus, from Latin -idus, from Proto-Italic *-iðos.

Ancestry of “trepido”, step by step

Step	Language	Word	Meaning
1	Latin	trepidus	nervous, jumpy, agitated; perilous, alarming
2	Latin	-idus	tending to
3	Proto-Italic	*-iðos	—