WordNet sense 1 (a reduction in the gross amount on which a tax is calculated; reduces taxes by the percentage fixed for the taxpayer's income bracket):

tax write-off, tax deduction

WordNet sense 2 (an amount or percentage deducted):

discount, discount

WordNet sense 3 (something that is inferred (deduced or entailed or implied)):

entailment, implication

WordNet sense 4 (reasoning from the general to the particular (or from cause to effect)):

synthesis, deductive reasoning

WordNet sense 5 (the act of reducing the selling price of merchandise):

price reduction

WordNet sense 6 (the act of subtracting (removing a part from the whole)):

subtraction