'thick-billed' originates from English, specifically the words 'thick' (Old English 'þicce') and 'bill' (Old English 'bile'), where 'thick' meant 'dense' and 'bill' meant 'beak'.

'thick' changed from the Old English word 'þicce' and 'bill' changed from the Old English word 'bile'; these elements were combined in Modern English to form the compound adjective 'thick-billed'.

Initially it literally combined the senses of 'thick' and 'bill' to mean 'having a thick bill'; over time it has remained a descriptive term, especially used for birds, to mean 'having a stout or broad beak'.