'heavy-billed' originates from Modern English, specifically the words 'heavy' and 'bill', where 'heavy' ultimately comes from Old English 'hefig' meaning 'weighing a lot' and 'bill' (in the sense 'beak') comes from Old English 'bile' (with influence from Old Norse forms).

'heavy' changed from Old English word 'hefig' to Middle English 'hevy' and eventually became the modern English word 'heavy'. 'Bill' (sense 'beak') changed from Old English 'bile' (and related Old Norse forms) into Middle English 'bil' and then modern English 'bill'. The compound 'heavy-billed' is a descriptive Modern English formation used in natural history and ornithology from roughly the 18th–19th centuries onward.

Initially, 'heavy' meant 'weighing a lot' and 'bill' meant 'beak'; over time the compound came to be used specifically to describe birds as 'having a large or robust beak' with little change in the core senses of the elements.