'three-lobed' originates from Modern English as a compound of 'three' and 'lobed', where 'three' ultimately comes from Old English 'þrīe' (meaning '3') and 'lobed' is formed from 'lobe' which comes from Latin 'lobus' (meaning 'lobe, rounded projection').

'three' developed from Old English 'þrīe' (from Proto-Germanic *þrīz), while 'lobe' entered English via Old French/Medieval Latin from Latin 'lobus'; the adjective form 'lobed' (meaning 'having lobes') combined with 'three' in Modern English to form the compound 'three-lobed'.

Initially the element 'lobe' meant 'a rounded projection or segment' in Latin, and the compound 'three-lobed' has retained the straightforward meaning 'having three lobes' in modern usage.