Polyimide

Part of speech: noun

Definitions

1. A heat-resistant synthetic polymer whose molecular chains contain imide groups, used in electronics, aerospace and high-temperature insulation
2. A high-performance plastic built from repeating imide linkages that resists extreme heat and is often used as a flexible circuit substrate
3. A thermally stable synthetic material formed from imide units, valued in aircraft parts, wire coatings and flexible printed circuits

Etymology: Polyimide is a modern chemical coinage, built from two pieces that each have their own story. The "poly-" comes from ancient Greek "polús", meaning "many", which chemists use to mark a molecule built from many repeating units. The "imide" part is older and more tangled. It traces back through "ammonia" to Ammon, the Egyptian god whose sanctuary in the Libyan desert was famous in antiquity and was associated with the Greek god Zeus. The Greeks called him "Ammon", and Latin speakers turned that into "ammoniacus", used for a resin gathered near his shrine. Chemists later applied "ammonia", named after that salt, as the root of a whole family of nitrogen-containing compounds. The suffix "-ide" was attached to that stem to name a class of chemical compounds, and "imide" was formed as one such name. Polyimide, then, is a compound name: many imide units joined into one long chain. It describes a class of heat-resistant polymers, so the name is a precise technical description rather than an old word that drifted in meaning.