It is traditionally assumed that metonymy plays hardly any role outside the lexicon, and is thus largely irrelevant to grammar. The present paper attempts to show the contrary: that metonymy has a series of long-ranging ramifications in the grammatical system. By specifically considering the role of metonymy in motivating certain phenomena in the English TENSE-ASPECT-MOOD (TAM) system, the paper demonstrates that the metonymic operations at play in this system form an orderly and internally coherent system. (Mario Brdar)