say it: mayn
main is an adjective and noun meaning "most important element". It carries 5 recorded senses.
(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”
grammar
any very large body of (salt) water
a principal pipe in a system that distributes water or gas or electricity or that collects sewage
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for main come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.