sub·strac·tion \-kshən\noun (-s) Etymology: Medieval Latin substraction-, substractio, from Late Latin substractus (past participle) + Latin -ion-, -io -ion 1.: subtraction < rendering back to us with additions or substractions, the beauty which existing things have of themselves presented to him — Thomas Carlyle > 2.: secret misappropriation of property and especially from a decedent's estate : embezzlement