'square-toed' originates from English, a compound of the adjective 'square' and the noun 'toe'. 'square' in English ultimately comes from Latin 'quadratus' (via Old French forms) where 'quadr-' related to 'four' or 'a square', and 'toe' comes from Old English 'tā' (from Proto-Germanic *tō).

'square' changed from Old French/Anglo-Norman forms (e.g. 'esquare'/'esquarre') into Middle English 'squar(e)' and then modern English 'square'; 'toe' was Old English 'tā' which evolved into modern 'toe'. The compound adjective 'square-toed' developed in modern English as a descriptive term for footwear.

Initially, 'square' referred to the geometric shape (related to 'four' / 'quadratus') and 'toe' referred to the foot digit; over time the compound came to mean 'having a toe shaped like a square' and, by extension in fashion contexts, 'conservative or old-fashioned in appearance'.