say it: bawl-GAYM
ballgame is a noun meaning "a particular situation that is radically different from the preceding situation". It carries 2 recorded senses.
a particular situation that is radically different from the preceding situation
“HDTV looks the same but it's really a whole new ballgame”
a field game played with a ball (especially baseball)
baseball
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 ballgame 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.