The Spanish word 'regionalismo' (meaning 'regionalism') can be traced back to the Latin verb 'regere', meaning 'to rule' or 'to direct'. From this verb came the Latin noun 'regio' meaning 'direction' or 'region', which then developed into the Latin adjective 'regionalis' meaning 'of a region'. The Spanish adjective 'regional' comes directly from this Latin word. The final form 'regionalismo' was created by adding the Spanish suffix '-ismo' (meaning 'doctrine' or 'system') to 'regional', thus creating a word that refers to a political or cultural system focused on regions.

Several simpler and more common Spanish words share this etymology. The basic word 'región' (region) comes directly from Latin 'regio'. The adjective 'regional' is also more commonly encountered than 'regionalismo'. Another related word is 'regir' (to rule, to govern), which comes from the same Latin root 'regere'.

English speakers can easily relate this word to several familiar English terms. The most obvious cognates are 'region' and 'regional', which share the exact same Latin ancestry. The English word 'reign' (to rule as a monarch) also comes from the same Latin root 'regere', though it took a different path through Old French. Other related English words include 'regulate', 'regiment', and 'rector', all ultimately derived from Latin 'regere' meaning 'to rule or direct'.