The Spanish word 'dedo' meaning 'finger' comes directly from the Latin word 'digitus', which also meant 'finger'. Over time, as Latin evolved into Spanish, 'digitus' underwent phonetic changes: the 'gi' sound simplified to 'e', and the final '-tus' was reduced to '-do', resulting in the modern Spanish form 'dedo'.

While 'dedo' itself is a fairly basic Spanish word, it appears in many common Spanish compounds and expressions. For example, 'dedal' means 'thimble' (literally something that goes on a finger), and 'dedillo' is a diminutive form meaning 'little finger'.

English speakers might recognize the Latin root 'digitus' in words like 'digit' (which can refer to both a number and a finger), 'digital' (originally relating to fingers, now commonly associated with computer technology), and 'digitate' (having finger-like projections). The connection between fingers and numbers exists because people historically used their fingers for counting.