The Spanish word 'pos' meaning 'after' comes directly from the Latin word 'post' which had the same meaning. Over time, the final 't' was dropped in Spanish, simplifying the pronunciation while maintaining the original meaning of indicating something that follows or comes after.

Some common Spanish words that share this etymology include 'después' (meaning 'after' or 'afterwards'), which combines 'de-' (from) and the same root 'pos-'. Another related word is 'posterior' (meaning 'later' or 'posterior'), which maintains more of the original Latin form.

English speakers might recognize this root in many common words like 'post-' (as in 'postwar', 'postgraduate'), 'posterior', and 'postpone'. All these words carry the basic meaning of 'after' or 'later'. The English language preserved the 't' from the original Latin 'post', while Spanish simplified it to 'pos'.