The Spanish word 'extraterrestre' (meaning 'extraterrestrial') comes from combining two Latin elements: 'extra' meaning 'outside' or 'beyond', and 'terrestre' (meaning 'terrestrial' or 'of the earth'). The word 'terrestre' itself comes from the Latin 'terrestris', which was formed from 'terra' (meaning 'earth' or 'land') and the suffix '-estris' (meaning 'pertaining to'). So literally, 'extraterrestre' means 'beyond the earth' or 'outside of what pertains to earth'.

This construction perfectly reflects its modern meaning of 'extraterrestrial' - referring to anything that comes from or exists beyond our planet Earth.

Some related Spanish words that might be familiar to Spanish learners include 'tierra' (earth, ground, soil) and 'terrestre' (terrestrial). These words all share the Latin root 'terra'. While 'tierra' refers directly to the earth or ground, 'terrestre' specifically means 'relating to the earth' or 'terrestrial', and adding 'extra-' creates 'extraterrestre' to mean 'beyond Earth'.

English speakers can easily relate this word to several familiar English words: 'extraterrestrial', 'terrestrial', and 'terrain'. All these words come from the same Latin root 'terra'. 'Terrain' refers to the physical features of a tract of land, while 'terrestrial' means 'of or relating to the earth'. The prefix 'extra-' is also commonly used in English in words like 'extraordinary' or 'extracurricular', always carrying the meaning of 'outside' or 'beyond'.