Where does “ides” come from?

ides (French) comes from Latin idus, from Swedish id, from Old Swedish idhe, from Old Norse *iði, from Old Norse iðja, from Old Norse ið — work; a restless motion.

Ancestry of “ides”, step by step

Step	Language	Word	Meaning
1	Latin	idus	The ides; in the Roman calendar the fifteenth day...
2	Swedish	id	effort, work, occupation; the tree "Taxus...
3	Old Swedish	idhe	—
4	Old Norse	*iði	—
5	Old Norse	iðja	to be active, do, perform
6	Old Norse	ið	work; a restless motion

Every word from Old Norse ið →Every word from Old Norse iðja →Every word from Old Norse *iði →