Workfellow is a compound of work + fellow ('companion, associate'); work is from Old English weorc, and fellow from Old Norse félagi ('partner, one who lays down money jointly'). In current use it is a noun meaning "a fellow worker; a colleague". That sense is explained by the older material without requiring a speculative semantic step: the inherited or borrowed base supplies the field of meaning, while the English formation fixes its modern role. The surface form is compositional: its joined elements remain visible in the modern word. The historical chain includes Old English weorc and Old Norse félagi. Related English forms include work and fellow. The word's history is thus visible in its construction: the components remain interpretable even after the whole expression has settled into a conventional English meaning.