electric discharge vs arc

electric discharge and arc both are nouns.

Word	Noun	Adjective	Verb	Adverb
electric discharge	Yes	No	No	No
arc	Yes	No	Yes	No

As nouns, electric discharge and arc are synonyms defined as:

electric discharge and arc: electrical conduction through a gas in an applied electric field

Other synonyms of electric discharge include discharge, electric arc, spark.

electric discharge (noun)	arc (noun)
electrical conduction through a gas in an applied electric field	electrical conduction through a gas in an applied electric field
	a continuous portion of a circle
	something curved in shape

electric discharge (verb)	arc (verb)
	form an arch or curve