'iamb' originates from Greek, specifically the word 'iambos' (ἴαμβος), where 'iambos' meant 'a kind of verse or metrical unit used in Greek poetry.'

'iamb' changed from Greek 'iambos' to Latin 'iambus' and entered Middle English as 'iamb', eventually becoming the modern English 'iamb'.

Initially, it referred to a kind of Greek verse or satirical poem and the metre used in it; over time it narrowed to mean specifically the metrical foot with an unstressed syllable followed by a stressed syllable.