The Spanish word 'retraso' (meaning 'delay') comes from the verb 'retrasar' ('to delay'). This verb was formed by combining the prefix 're-' (meaning 'back' or 'again') with 'tras' (meaning 'behind'), plus the verbal suffix '-ar'. The element 'tras' itself evolved from Latin 'trans' (meaning 'across'). The combination of these elements creates a sense of 'moving back behind' or 'falling behind', which developed into the modern meaning of delay or lateness.

A simpler and very common Spanish word that shares this etymology is 'tras', meaning 'behind' or 'after'. You can see how both 'retraso' and 'tras' share the basic concept of something being behind - whether physically (tras) or in terms of time (retraso). Another related word is 'trasero' meaning 'rear' or 'back part', which also carries this same spatial concept.

English speakers might recognize the connection to words containing 'trans-', which comes from the same Latin root. Words like 'transport' (carry across), 'transfer' (carry across/over), and 'transcend' (climb across/beyond) all share this ancient Latin ancestor 'trans'. While these English words emphasize movement across or beyond something, the Spanish 'retraso' developed to focus on the concept of falling behind or being delayed.