The word 'subtract' means to take away or deduct from a total. Antonyms for 'subtract' include words like add, increase, expand, augment, multiply, and amplify. These words are opposite to the concept of subtracting and entail adding or increasing something. For instance, if you add 2 and 4, you get 6, which is the opposite of subtracting 4 from 6 to get 2. Similarly, when you multiply a number, you are adding multiples of it, while division involves taking multiples of the number away. Thus, the antonyms for 'sub-tract' refer to actions or operations that increase or amplify a quantity, rather than decreasing it.