imprison vs lag

imprison is not a noun while lag is a noun.

Word	Noun	Adjective	Verb	Adverb
imprison	No	No	Yes	No
lag	Yes	No	Yes	No

As verbs, imprison and lag are synonyms defined as:

Other synonyms of imprison include gaol, immure, incarcerate, jail, jug, put away, put behind bars, remand.

imprison (noun)	lag (noun)
	the act of slowing down or falling behind
	one of several thin slats of wood forming the sides of a barrel or bucket
	the time between one event, process, or period and another

imprison (verb)	lag (verb)
lock up or confine, in or as in a jail	throw or pitch at a mark, as with coins
confine as if in a prison	cover with lagging to prevent heat loss
	hang (back) or fall (behind) in movement, progress, development, etc.
	lock up or confine, in or as in a jail