Jag

jag \ˈjag\ transitive verb: 1. to cut indentations into, 2. to form teeth on (a saw) by cutting indentations
intransitive verb: 1. prick, thrust,
2. to move in jerks
noun: a sharp projecting part; barb

Etymology: Middle English jaggen

I only ever hear this word used as a past participle modifying a noun, where it means “having a sharply uneven edge or surface” (jagged peaks)
or “having a harsh, rough or irregular quality” (jagged rhythms).