The Spanish word 'allá' meaning 'there' comes from Latin 'illac' meaning 'through there' or 'that way', which itself developed from the Latin demonstrative pronoun 'ille' meaning 'that' or 'those'. The evolution from 'illac' to 'allá' involved phonetic changes common in the development from Latin to Spanish, where the initial 'i' changed to 'a' and the final 'c' softened to become 'á'.

Several common Spanish words share this Latin root, including 'allí' (there), 'ella' (she), and 'él' (he). All these words derive from the Latin demonstrative 'ille'. While 'allá' indicates a more general or distant 'there', its cousin 'allí' indicates a more specific location. The pronouns 'ella' and 'él' retained the pointing-out or demonstrative function of 'ille' but evolved to become personal pronouns.

While English doesn't have direct cognates of 'allá', we can find some related words that entered English through French, which also inherited words from the Latin 'ille'. For example, the English pronoun 'elle' (used in legal language) comes from the French 'elle' (she), which shares the same Latin root 'ille' as Spanish 'allá'. Another example is the English word 'else', which ultimately derives from the same Proto-Indo-European root that gave us Latin 'ille'.