Deduction

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. 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."

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."