declension

In linguistics, declension is the occurrence of inflection in nouns, pronouns and adjectives, indicating such features as number (typically singular vs. plural), case (subject, object, and so on), gender, and possession.

-s

Declension occurs in a great many of the world's languages, and features very prominently in many European languages, but is much less prominent in English. English nouns decline only to distinguish singular from plural (e.g., book vs. books); only very few English adjectives decline (the French loan-word blond(e) being a rare exception), and only a few English pronouns show vestiges of case-triggered declension (e.g., nominative case he, dative case or accusative case him, genitive case (possessive case) his). As detailed below, English was once a highly inflected language, as befitting its Indo-European and especially its Germanic linguistic ancestry, but it became greatly simplified as it evolved.