Nominative is a grammatical case for a noun. Nominative marks, generally, the subject of a verb. Nominative cases are found in Latin and Old English, among other languages. English still retains some nominative pronouns, as opposed to the accusative case: I (accusative me), we (accusative us), he (accusative him), she (accusative her), you (archaic accusative ye) and they (accusative them). An archaic usage is the singular second-person pronoun thou (accusative thee).
Compare accusative case, dative case, ergative case, genitive case, vocative case, ablative case.