'latecomer' originates from Modern English as a compound of 'late' + 'comer', where 'late' ultimately traces to Old English 'læt' meaning 'slow' and 'come' (in 'comer') traces to Old English 'cuman' meaning 'to come'.

'late' came from Old English 'læt' and 'come' from Old English 'cuman'; in Middle English these elements existed as 'late' and forms of 'come', and they combined in Modern English to give the compound 'latecomer'.

Initially the component words meant 'slow' and 'one who comes'; the compound has long carried the straightforward meaning 'a person who arrives late', with little shift in core sense.