The word 'weird' traces its lineage to the Old English 'wyrd', meaning fate or destiny, a concept central to Germanic and Norse mythology. This noun evolved from the Proto-Germanic 'wurđiz', which is itself derived from the Proto-Indo-European root 'wert-', meaning 'to turn, to wind'. The connection lies in the idea of the turning or weaving of the threads of fate. The modern adjective meaning 'strange and supernatural' emerged from its association with the 'Weird Sisters', the three fates in Shakespeare's Macbeth, who controlled human destiny and were portrayed as uncanny, prophetic beings. Thus, the sense shifted from the abstract concept of fate to the eerie and unnatural quality attributed to its agents.

The word 'weird' is a simplex word. It originates from the Old English noun 'wyrd' (fate, destiny), which is related to the Old Norse 'urðr' (one of the Norns, a goddess of fate). Its functional role is as a complete lexical unit.