The noun main has 2 senses (no senses from tagged texts)
1. main, briny -- (any very large body of (salt) water)
2. main -- (a principal pipe in a system that distributes water or gas or electricity or that collects sewage)
Overview of adj main
The adj main has 3 senses (first 1 from tagged texts)
1. (36) chief, main, primary, principal -- (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. independent, main -- ((of a clause) capable of standing syntactically alone as a complete sentence; "the main (or independent) clause in a complex sentence has at least a subject and a verb")
3. main -- (of force; of the greatest possible intensity; "by main strength")