This book deals with one aspect of Greek and Proto-Indo-European nominal morphology, the formation, inflection and semantics of s-stem nouns and adjectives. It uncovers the mechanisms of their creation and shows their limitation. The established view that the nouns are an unproductive category is challenged; at the same time, the expanding and partly changing nature of the basis governing the creation of the adjectives is explained. Morphology and semantics are studied in tandem, and a large chronological span of the Greek language is covered. The historical side is then extended into prehistory, and in particular the Greek evidence is tested against recent theories on Proto-Indo-European ablaut, leading to a reassessment of the morphonological characteristics in question.