say it: RAT-uhl-snayk
rattlesnake is a noun meaning "pit viper with horny segments at the end of the tail that rattle when shaken". It is pronounced /ˈɹætəlˌsneɪk/ — RAT-uhl-snayk. It carries one recorded sense.
pit viper with horny segments at the end of the tail that rattle when shaken
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 rattlesnake 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.