Adjective
1. most important element;
"the chief aim of living""the main doors were of solid glass""the principal rivers of America""the principal example""policemen were primary targets"2. of a clause; able to stand alone syntactically as a complete sentence;
"the main (or independent) clause in a complex sentence has at least a subject and a verb"3. of force; of the greatest possible intensity;
"by main strength"