A precise arrangement of three neighboring phosphor elements, emitting red, green, and blue light, used in cathode ray tubes and early emissive displays. When excited by an electron beam, the triad relies on the spatial blending of the human eye to produce a full gamut of colors for that specific pixel. The pitch and alignment of these triads directly dictate the resolution and color fidelity of the display.
Heard on the job
If you look closely at the old broadcast monitor with a loupe, you can see the individual RGB triads firing.