How to use main in a sentence. The chief or principal part or point: [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. 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. The meaning of main is physical strength : The principal or most important part or point usually in the phrase in the main, mostly, chiefly A pipe that carries…. The main of their investments was lost during the war. Most important or largest: The main thing is to keep calm and don’t get angry. · main (not comparable) of chief or leading importance; Sheer or utmost (esp in the phrase by main force) Physical strength, power, or force: Main (meɪn) adj (prenominal) 1. Main refers to the primary or most important aspect or part of something. Chief or principal in rank, importance, size, etc 2. The most important fact in a situation: Force —used in the phrase with might and main. To struggle with might and main.