'anorectal-oral' is a compound formed from 'anorectal' + 'oral'. 'anorectal' combines the prefix 'ano-' (from Greek 'anō', relating to the anus) and 'rectal' (from Latin 'rectum'), while 'oral' originates from Latin words for 'mouth' (Latin 'ōs/ōris' or adjective 'oralis').

'anorectal' was formed in modern medical Latin/English by combining classical roots ('ano-' + 'rectal') in medical usage from the 19th–20th century; 'oral' entered English via Latin 'ōs/ōris' and related Old French/Latin adjectival forms before stabilizing as English 'oral'. The compound 'anorectal-oral' is a modern descriptive formation used in medical and epidemiological contexts.

Initially the component roots named anatomical regions ('anus/rectum' and 'mouth'), but over time the compound has come to be used specifically to describe routes of contact or transmission linking those regions (e.g., transmission from anorectal sites to the oral cavity).