'climax' originates from Greek, specifically the word 'klimax' (κλίμαξ), where 'klim-' meant 'ladder' or 'staircase'.

'climax' passed into Latin and Medieval Latin as 'climax' and then into English via Late Latin/Old French; the sense shifted from a literal 'ladder' to a figurative 'ladder' of events or grades and eventually to the modern sense of 'peak' or 'culmination'.

Initially, it meant 'ladder' or 'stair'; over time it evolved to mean 'a highest point or culmination' and later took on additional senses such as sexual 'orgasm'.