Main refers to the primary or most important aspect or part of something. The main of their investments was lost during the war. · main (not comparable) of chief or leading importance; Chief or principal in rank, importance, size, etc 2. [from 15th c. ] quotations the main office is actually one of the smaller rooms. Find 561 different ways to say main, along with antonyms, related words, and example sentences at thesaurus. com. The principal or most important part or point usually in the phrase in the main, mostly, chiefly Sheer or utmost (esp in the phrase by main force) It signifies the central or principal focus, significance, or purpose of a subject or object. The main social event of the summer was a dance and reception. A pipe that carries…. Force —used in the phrase with might and main. To struggle with might and main. Most important or largest: The chief or principal part or point: How to use main in a sentence. Physical strength, power, or force: The most important fact in a situation: Main (meɪn) adj (prenominal) 1. The main thing is to keep calm and don’t get angry. The meaning of main is physical strength :