The Nominative Case - Learning Latin
https://www.thoughtco.com/nominative-case-in-latin-11942417.12.2008 · Nominative With To Be Verbs . If you were to use the sentence "The girl is a pirate," both the words for girl and pirate would be nouns in the Nominative Singular. That sentence would be "puella pirata est." Pirate is a predicate nominative.The actual sentence was "puella bona est" where both the noun for girl, puella, and the adjective for good, bona, were in the Nominative …
Nominative case - Wikipedia
https://en.wikipedia.org/wiki/Nominative_caseIn grammar, the nominative case (abbreviated NOM), subjective case, straight case or upright case is one of the grammatical cases of a noun or other part of speech, which generally marks the subject of a verb or the predicate noun or predicate adjective, as opposed to its object or other verb arguments. Generally, the noun "that is doing something" is in the nominative, and the nominative is often the form listed in dictionaries.