1899, from bifocals with tri-.
"bifocal spectacles," 1883, bi-focals; see bifocal. Invented by Benjamin Franklin, but he called them double spectacles.
word-forming element meaning "three, having three, once every three," from Latin tres (neuter tria) or Greek treis, trias "three" (see three).
updated on February 16, 2014
英语词源词典收录了45867条英语词源词条,基本涵盖了全部常用英语词汇的起源、历史,是研究英语词汇或通过词源学英语的必备工具。