The Spanish verb 'vagar' (to wander, be idle) comes from two related Latin verbs: 'vacare' meaning 'to be empty or free' and 'vagari' meaning 'to wander or roam'. The semantic connection between these meanings is quite intuitive - when one is free or has empty time, they are able to wander or roam about. Over time, this also developed the connotation of being idle or inactive in Spanish.

A common related Spanish word is 'vacación' (vacation), which comes from the same Latin root 'vacare'. Just as 'vagar' refers to having free time to wander, 'vacación' refers to a period of free time away from work or studies. Another related word is 'vacante' (vacancy), which maintains the original sense of emptiness or being unoccupied.

English speakers can connect 'vagar' to several familiar words. 'Vagrant' and 'vagabond' both come from the Latin 'vagari' and refer to people who wander without a fixed home. The word 'vacation' is related through the Latin 'vacare', as it represents a time when we are free from our usual duties. Even the word 'vacant' shares this root, maintaining the original meaning of being empty or unoccupied.