borderline vs circuit

borderline and circuit both are nouns.

Word	Noun	Adjective	Verb	Adverb
borderline	Yes	Yes	No	No
circuit	Yes	No	Yes	No

As nouns, circuit is a hyponym of borderline; that is, circuit is a word with a more specific, narrower meaning than borderline:

Other hyponyms of borderline include circumference, fence line, property line, state boundary, state line.

borderline (noun)	circuit (noun)
a line that indicates a boundary	a journey or route all the way around a particular place or area
	movement once around a course
	an electrical device that provides a path for electrical current to flow
	a racetrack for automobile races
	(law) a judicial division of a state or the United States (so-called because originally judges traveled and held court in different locations); one of the twelve groups of states in the United States that is covered by a particular circuit court of appeals
	an established itinerary of venues or events that a particular group of people travel to
	the boundary line encompassing an area or object

borderline (adjective)	circuit (adjective)
of questionable or minimal quality

borderline (verb)	circuit (verb)
	make a circuit