Deduct
late Middle English: from Latin deduct- ‘taken or led away’, from the verb deducere . Deduct and deduce were not distinguished in sense until the mid 17th century.
wiktionary
Borrowed from Latin deductus, perfect passive participle of verb deducere(“lead from”).
etymonline
deduct (v.)
early 15c., "to take away, separate, or remove in estimating or counting," from Latin deductus, past participle of deducere "lead down, bring away;" see deduce, with which it formerly was interchangeable. Deduct refers to taking away portions or amounts; subtract to taking away numbers. Related: Deducted; deducting.
Deduct is to lead away, set aside, in a general or distributive sense; subtract, to draw off, remove, in a literal or collective sense. In settling a mercantile account, certain items, as charges, losses, etc. are deducted by being added together and their total subtracted from the grand total of the transaction. [Century Dictionary]
