deduction

Etymology

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

noun

1. That which is deducted; that which is subtracted or removed
2. A sum that can be removed from tax calculations; something that is written off
   You might want to donate the old junk and just take the deduction.
3. (logic) A process of reasoning that moves from the general to the specific, in which a conclusion follows necessarily from the premises presented, so that the conclusion cannot be false if the premises are true.
4. A conclusion; that which is deduced, concluded or figured out
   He arrived at the deduction that the butler didn't do it.
   An unkinder deduction, considering only the Select Committee's report and discounting rumours of wayward conclusions by the Stedeford Group, would be that if one inquisition doesn't produce the desired answers, the Minister's policy is "try, try again"—or should one say "fight, fight, fight again". 1961 January, “Talking of Trains: Marples out of step”, in Trains Illustrated, page 1
5. The ability or skill to deduce or figure out; the power of reason
   Through his powers of deduction, he realized that the plan would never work.