triad

noun

tri·​ad ˈtrī-ˌad 

 also  -əd

1

: a union or group of three : trinity

2

: a chord of three tones consisting of a root with its third and fifth and constituting the harmonic basis of tonal music

triadic

trī-ˈa-dik 

adjective

triadically

trī-ˈa-di-k(ə-)lē 

adverb

Did you know?

The best-known type of triad is a type of musical chord consisting of three notes. A D-major triad is made up of the notes D, F-sharp, and A; an F-minor triad is made up of F, A-flat, and C; and so on. Major and minor triads form the basis of tonal music, and songs and other pieces usually end with a triadic harmony. In medicine, a triad is a set of three symptoms that go together. The Chinese criminal organizations called triads got their name from the triangular symbol that they used back when they began, centuries ago, as patriotic organizations. Today, with over 100,000 members, the triads operate in the U.S., Canada, and many other countries.

Synonyms

• trio
• trinity

Examples of triad in a Sentence

a triad of candlesticks on the mantel

Recent Examples on the Web

The real Martinů giveaway is an underlying buzz of activity in the piano and the harp—D-minor triads mixed with C-sharp-minor, B-flat-major, and E-flat-major ones, suggesting a rickety machinery behind the lyrical action. —Alex Ross, New Yorker, 8 Sep. 2025

The March 2-3, 2026, total lunar eclipse will mark the third in a triad of consecutive total lunar eclipses within a lunar year. —Jamie Carter, Forbes.com, 7 Sep. 2025

Total lunar eclipses — which always occur during a full moon — often arrive in triads, accompanied by at least one solar eclipse two weeks before and/or after. —Jamie Carter, Space.com, 3 Sep. 2025

Worse, a third nuclear superpower, China, is turning the former dyad into a triad. —Andreas Kluth, Twin Cities, 17 Aug. 2025

Word History

Etymology

Latin triad-, trias, from Greek, from treis three

First Known Use

1546, in the meaning defined at sense 1

Rhymes for triad

• comrade
• dryad
• dyad
• forbad
• grandad
• granddad
• keypad
• nomad
• notepad
• postgrad
• sinbad
• tetrad

Kids Definition

triad

noun

tri·​ad ˈtrī-ˌad 

 also  -əd

1

: a union or group of three usually closely related persons or things

2

: a chord made up usually of the first, third, and fifth notes of a scale

triadic

trī-ˈad-ik 

adjective

Medical Definition

triad

noun

tri·​ad

ˈtrī-ˌad also -əd

1

: a union or group of three

a triad of symptoms

2

: a trivalent element, atom, or radical

triadic

trī-ˈad-ik 

adjective