say it: GAY-nur
gainer is a noun meaning "a person who gains weight". It carries 3 recorded senses.
a person who gains weight
a person who gains (gains an advantage or gains profits)
“she was clearly the gainer in that exchange”
a dive in which the diver throws the feet forward to complete a full backward somersault and enters the water feet first and facing away from the diving board
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 gainer 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.