Word-formation including conversion and affixation can be seen as metonymically motivated. We argue for a view of metonymy as an act of pragmatic, not lexical, nature. Thus, it does not result in polysemy but in temporary meaning extensions. The metonymy-based morphological changes can be either class-changing or class-preserving. We illustrate metonymy in Old English via kennings, also known as ‘poetic paraphrases’, like seglrad ‘sail road’, i.e. ‘sea’. In short, metonymy is to be recognized as a form of word-formation. A systematic diachronic comparison of metonymy-based inflectional and derivational patterns, just like the ones we present in English, will be illustrative of the whole process.