Meaning

noun a reduction in the gross amount on which a tax is calculated; reduces taxes by the percentage fixed for the taxpayer's income bracket

noun an amount or percentage deducted

noun something that is inferred (deduced or entailed or implied)

originFrom Middle French déduction, from Latin deductio. Equivalent to deduct + -ion or deduce + -tion.

Etymology from Wiktionary, CC BY-SA 3.0