'anhelous' originates from Latin, specifically the word 'anhelus' and the verb 'anhelāre,' where the intensive prefix 'an-' meant 'intensely' and 'halāre' meant 'to breathe.'

'anhelus' gave Late Latin 'anhelosus' ('panting, breathless'), which, by scholarly borrowing, eventually became the modern English word 'anhelous.'

Initially, it meant 'panting; out of breath,' and later also developed a figurative sense of 'eager or breathless with emotion,' while retaining the original physical sense.