triad vs common chord

triad and common chord both are nouns.

Word	Noun	Adjective	Verb	Adverb
triad	Yes	No	No	No
common chord	Yes	No	No	No

As nouns, triad and common chord are synonyms defined as:

triad and common chord: a three-note major or minor chord; a note and its third and fifth tones

triad (noun)	common chord (noun)
a three-note major or minor chord; a note and its third and fifth tones	a three-note major or minor chord; a note and its third and fifth tones
three people considered as a unit
a set of three similar things considered as a unit
the cardinal number that is the sum of one and one and one