Moire

Part of speech: noun

Pronunciation: /mwɑː/

Definitions

1. A fabric design showing a wavy or rippled effect that looks like water marks, often created by pressing or rolling; a visual pattern formed when two grids overlap and produce a series of dark and light bands as interference
2. A type of cloth featuring a watery, shimmering pattern usually made by heat or pressure; an optical effect that occurs when two repetitive patterns are superimposed causing a moiré interference
3. A textile surface decorated with flowing, undulating lines resembling ripples, often used in clothing or upholstery; a pattern created by the overlapping of similar repetitive designs, resulting in distortion or a new pattern due to interference

Etymology: The surprising twist is that "moire" began as a word for hair. Its source is "mohair," the fine silky wool of the Angora goat, which English borrowed from Arabic via Italian and Portuguese-influenced routes; French then took the English word and reshaped it into "moire," a fabric of watered or rippled texture. Over time the sense shifted from the material itself to the wavy surface pattern produced on silk or other cloth. The rippled look is the heart of the meaning. Pressing or rolling a fabric with heated engraved cylinders creates a watermark-like sheen, and that effect gave the word its name for the pattern rather than the fibre. The same wavy quality later became a term in optics and mathematics: when two fine grids or patterns are laid one over another, they produce dark and light bands, and these interference shapes are also called moire.