Where does “raidissement” come from?

raidissement (French) comes from French raidir, from French raide, from Old French roide, from Old French roit, from Latin rigidus, from Latin -idus, from Proto-Italic *-iðos.

raidissement (French): stiffening; tightening

Definitions

stiffening; tightening

Ancestry of “raidissement”, step by step

Step	Language	Word	Meaning
1	French	raidir	stiffen
2	French	raide	stiff, straight; steep, abrupt; stubborn
3	Old French	roide	—
4	Old French	roit	hard
5	Latin	rigidus	stiff, rigid, hard, inflexible; stern, strict,...
6	Latin	-idus	tending to
7	Proto-Italic	*-iðos	—

Every word from Proto-Italic *-iðos →Every word from Latin -idus →Every word from Latin rigidus →