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