Where does “-ida” come from?

-ida (Finnish) comes from Proto-Finnic -t'ak, from Proto-Uralic -ta- — Forms verbs from nouns; Forms causative verbs...

-ida (Finnish): [[Appendix:Eastern Finnish reflexive verbs

Definitions

Step	Language	Word	Meaning
1	Proto-Finnic	-t'ak	Forms verbs from nominal stems, generally with a causative, factitive or instrumental meaning
2	Proto-Uralic	-ta-	Forms verbs from nouns; Forms causative verbs...