The Spanish word 'bolsa' meaning 'bag' or 'purse' traces its origins back to Ancient Greek through Latin. It comes from the Latin word 'bursa' meaning 'leather bag', which itself was borrowed from the Greek word 'byrsa' (βύρσα) meaning 'leather' or 'hide'. The evolution from 'bursa' to 'bolsa' shows a common sound change in Spanish where 'ur' became 'ol', and the final 'a' was preserved.

The word 'bolsa' is a fundamental Spanish word and is used in many common compound words and phrases. For example, 'bolsillo' (pocket), 'bolso' (handbag), and 'reembolso' (refund) are all derived from 'bolsa'. The stock market in Spanish-speaking countries is also called 'la bolsa' because historically, merchants would meet to trade at the House of the Purse (Casa de la Bolsa).

English speakers might recognize this etymology in words like 'bursar' (a person who manages money at a college or university) and 'bursary' (a monetary grant), both of which come from the same Latin root 'bursa'. The word 'purse' itself, though it might look different, is also distantly related, having evolved from the same Latin word through Old English and Anglo-Norman French. Even the medical term 'bursa' (a fluid-filled sac that acts as a cushion between bones, tendons and muscles) comes from this same origin, named for its pouch-like shape.