arc vs electric arc

arc and electric arc both are nouns.

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

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

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

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

arc (noun)	electric 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

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