The Spanish preposition 'con' meaning 'with' comes directly from the Latin preposition 'cum', which meant 'with' or 'together'. This is a straightforward inheritance where the Latin 'm' at the end of 'cum' changed to 'n' in Spanish, a common sound change between these languages.

You'll see 'con' as a prefix in many Spanish words where it adds the meaning of 'with' or 'together', such as 'convivir' (to live together), 'compartir' (to share), and 'conectar' (to connect). Understanding that 'con' means 'with' will help you understand many compound Spanish words.

The Latin 'cum' is also the source of the English prefix 'co-' (and its variants 'com-', 'con-', and 'col-') which appears in many English words indicating togetherness or joint action. You can see this in words like 'cooperate' (to work together), 'companion' (someone you're with), 'collaborate' (to work together), and 'connect' (to join together). Recognizing this common origin can help you understand both Spanish and English words with these elements.