Drawing on a wide array of historical and contemporary corpora, this article provides one of the first empirical analyses of the intricately related functional changes that -ish underwent in the course of English language history. By investigating the distribution of -ish formations, the analysis sheds light on the productivity of the suffix, which does not only become evident in the numerous hapax legomena, but also in the trajectory of change itself in which -ish occurs with ever new base categories and new functions. Moreover, the article revisits theoretical claims made in the literature about the diachronic development and synchronic properties of -ish and reassesses them in the light of the corpus-based observations.