Pyrex (n.)

1915, proprietary name (Corning Glass Works, Corning, N.Y.) of a type of hard, heat-resistant glass, an arbitrary coinage, in which advertisement writers and eager etymologists see implications of Greek pyr "fire" and perhaps Latin rex "king;" but the prosaic inventors say it was based on pie (n.1), because pie dishes were among the first products made from it. The -r-, in that case, is purely euphonious.

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