object lesson vs monition

object lesson and monition both are nouns.

Word	Noun	Adjective	Verb	Adverb
object lesson	Yes	No	No	No
monition	Yes	No	No	No

As nouns, monition is a hypernym of object lesson; that is, monition is a word with a broader meaning than object lesson:

object lesson: punishment intended as a warning to others
monition: cautionary advice about something imminent (especially imminent danger or other unpleasantness)

Other hypernyms of object lesson include admonition, warning, word of advice.

object lesson (noun)	monition (noun)
punishment intended as a warning to others	a firm rebuke
	cautionary advice about something imminent (especially imminent danger or other unpleasantness)
	a summons issued after the filing of a libel or claim directing all parties concerned to show cause why the judgment asked for should not be granted