Roget's 21st Century Thesaurus, Third Edition Copyright © 2013 by the Philip Lief Group.

WORD ORIGIN

early 15c., from Latin deductus, past participle of deducere "lead down, bring away;" see deduce, with which it formerly was interchangeable. Technically, deduct refers to taking away portions or amounts; subtract to taking away numbers. Related: Deducted; deducting.