'buckle' originates from Latin, specifically the word 'buccula', where 'bucca' meant 'cheek' and 'buccula' was a diminutive meaning 'little cheek-strap' or 'cheek piece'.

'buccula' changed into Old French forms such as 'bocle'/'bucel' and later Old French 'bucle'/'bocle', which entered Middle English as 'bocle'/'bukel' and eventually became the modern English word 'buckle'.

Initially it meant 'a cheek-strap or small strap' (a part of horse tack), but over time it evolved to mean 'a metal clasp or fastening' and then the verb sense 'to fasten with a buckle' and extended metaphorically to 'give way under pressure'.