Where does “rigida” come from?

rigida (Latin) comes from Latin rigidus, from Latin -idus, from Proto-Italic *-iðos.

rigida (Latin): nominative feminine singular of rigidus;...

Definitions

Step	Language	Word	Meaning
1	Latin	rigidus	stiff, rigid, hard, inflexible; stern, strict,...
2	Latin	-idus	tending to
3	Proto-Italic	*-iðos	—

rigida — Etymology, Origin & Word History | Etymology Explorer