The Spanish word 'lejos' (meaning 'far') comes from the Old Spanish 'lexos', which developed from the Latin comparative adverb 'laxius' meaning 'more widely'. 'Laxius' itself was derived from the Latin adverb 'laxe' ('loosely, widely'), which came from the Latin adjective 'laxus' meaning 'wide, loose, spacious'.

The semantic evolution from 'wide/loose' to 'far' makes intuitive sense - something that is widely spaced or spread out covers a greater distance, and thus the concept of width or looseness gradually shifted to express the idea of distance or farness in Spanish.

A related Spanish word is 'laxo' (meaning 'loose, slack, lax'), which comes more directly from the Latin 'laxus'. While 'lejos' took on the meaning of physical distance, 'laxo' retained the original Latin sense of looseness or lack of tightness.

English speakers might recognize the connection to words like 'lax' and 'relax', which also come from Latin 'laxus'. While 'lejos' developed to describe physical distance in Spanish, the English descendants maintained meanings related to looseness, either literally (as in something being loose or slack) or figuratively (as in being relaxed or not strict).