'intestineless' originates from Modern English, formed by combining 'intestine' and the suffix '-less'. 'Intestine' ultimately comes from Latin 'intestinus'/'intestinum' (from 'intus' meaning 'within'), and '-less' comes from Old English 'lēas' meaning 'without'.

'intestine' passed into English via Latin (and Old/Medieval French/Latin forms) into Middle English as 'intestine'; the suffix '-less' comes from Old English 'lēas' and remained productive in forming adjectives. The compound 'intestineless' is a modern English formation using these elements.

Initially, Latin 'intestinus' meant 'internal' (from 'within') and later designated the organ we call the intestine; the suffix '-less' has long meant 'without', so the combined modern meaning is 'without intestines'.