Noun

• S: (n) main, briny (any very large body of (salt) water)
• S: (n) main (a principal pipe in a system that distributes water or gas or electricity or that collects sewage)

Adjective

• S: (adj) chief, main, primary, principal, master (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"; "the master bedroom"; "a master switch"
• S: (adj) 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"
• S: (adj) main (of force; of the greatest possible intensity) "by main strength"