The Spanish word 'pues' comes from the Latin word 'post', which meant 'after' or 'behind'. Over time, this spatial and temporal meaning evolved in Spanish to become a conjunction and discourse marker meaning 'then', 'since', or 'because'. This semantic shift from a physical/temporal position to a logical connector is a common pattern in language evolution, where concrete meanings often develop into more abstract ones.

Some related Spanish words that preserve the original 'after/behind' meaning include 'después' (after, afterward) and 'posterior' (posterior, later), though these came through different derivational paths from the same Latin root.

In English, we can find several words derived from the same Latin 'post-' root, such as 'post' itself (as in 'post office' or 'to post a letter'), 'posterior' (meaning the back part), and 'postscript' (written after, P.S.). The prefix 'post-' in words like 'postwar', 'postgraduate', and 'postpone' also carries this original meaning of 'after' or 'behind'.