What is the meaning of Triad?

A grouping of three.

A word of three syllables.

A branch of a Chinese underground criminal society, mostly based in Hong Kong.

On a CRT display, a group of three neighbouring phosphor dots, coloured green, red, and blue.

A chord consisting of a root tone, the tone two degrees higher, and the tone four degrees higher in a given scale OR any chord with three notes.

Source: wiktionary.org