say it: ahn-STAYJ
onstage is an adjective and adverb meaning "situated or taking place on the area of a stage visible to the audience". It carries 2 recorded senses.
situated or taking place on the area of a stage visible to the audience
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 onstage 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.