The Spanish verb 'tostar' (meaning 'to toast') comes from Latin 'tostare', which meant 'to dry' or 'to parch'. This Latin verb was derived from 'tostum', the supine form of the Latin verb 'torrere', which meant 'to dry, parch, or burn'. The evolution from Latin to Spanish maintained both the form and meaning quite closely, with the basic concept of applying heat to dry or cook something remaining central to the word's meaning.

Some related Spanish words include 'tostada' (a toasted tortilla), 'tostador' (toaster), and 'tostón' (a toasted plantain slice). All these words share the same root and relate to the process of toasting or cooking until brown.

English speakers might recognize the connection to words like 'toast' and 'torrid'. 'Toast' comes from the same Latin root 'tostum', while 'torrid' (meaning very hot and dry) comes from 'torrere'. The word 'torrent' also shares this ancient connection, originally referring to burning or drying, though its meaning shifted to rushing water. These connections show how the ancient concept of heat and drying branched into different but related meanings in modern languages.