say it: di-PLOH-mah
diploma is a noun meaning "a document certifying the successful completion of a course of study". It carries one recorded sense.
a document certifying the successful completion of a course of study
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 diploma 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.