The verb 'spin' originates from the Old English 'spinnan', meaning "to draw out and twist fibers into thread." This Old English term is part of the wider Proto-Germanic family, from the root spenwaną, which carried the same essential meaning. The specific past tense form 'spun' developed through regular sound changes in Middle English, solidifying as the standard form for the simple past and past participle. The core concept of rotating or twisting, from the literal act of making thread, extends metaphorically to modern abstract uses like spinning a tale or a web.

The word 'spun' is a single, unsegmentable morpheme representing the past tense and past participle form of the verb 'spin'. It is derived from Old English 'spinnan'.