Entry 1 sense Webster, 1913 Copious /kōp'-ē-əs/ · Co·pi·ous · IPA /ˈkoʊ.pi.əs/ 01 a. Large in quantity or amount; plentiful; abundant; fruitful. 1. Large in quantity or amount; plentiful; abundant; fruitful. “Kindly pours its copious treasures forth.” — Thomson. “Hail, Son of God, Savior of men! thy name Shall be the copious matter of my song.” — Milton. Syn. Ample; abundant; plentiful; plenteous; rich; full; exuberant; overflowing; full. See Ample.