'paresis' originates from Greek, specifically the word 'parēsis' (παρέσις), where 'para-' meant 'beside' and the suffix '-ēsis' denoted 'a condition or action'.

'paresis' passed into Late Latin/medical Latin as 'paresis' and was adopted into English through medical usage in the 18th–19th centuries, becoming the modern clinical term for partial paralysis.

Initially, it meant 'loosening' or 'letting go' (a slackening of control), but over time it evolved into the current medical meaning of 'partial paralysis' or 'muscle weakness'.