say it: kuhn-grach-uh-LAY-shuhn
congratulation is a noun meaning "the act of acknowledging that someone has an occasion for celebration". It carries 2 recorded senses.
the act of acknowledging that someone has an occasion for celebration
(usually plural) an expression of pleasure at the success or good fortune of another
“I sent them my sincere congratulations on their marriage”
plural
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 congratulation 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.