The Spanish word 'pareja' meaning 'pair' or 'couple' comes from the Latin word 'paricula', which was a diminutive form of the Latin word 'par' meaning 'equal' or 'pair'. The Latin diminutive suffix '-icula' was added to 'par' to form 'paricula', literally meaning 'small pair'. Over time, as Latin evolved into Spanish, 'paricula' underwent phonetic changes to become the modern Spanish word 'pareja'.

A related and simpler Spanish word is 'par', which directly comes from the Latin 'par' and means 'pair' or 'even number'. While 'par' is used more in mathematical or technical contexts, 'pareja' is more commonly used for couples or matched pairs in everyday language.

Several common English words share the same Latin root 'par'. The word 'pair' is a direct descendant, while 'par' (as in golf or par value) comes from the same source, carrying the original meaning of 'equal'. The word 'peer' (meaning an equal in rank or status) also derives from this Latin root. Even the word 'parity' (meaning equality or equivalence) comes from this same Latin ancestor.