hornless
Word family
Synonym discussion
Sense: adjective/1
All three words relate to the absence of horns on animals, but they differ in meaning and context. 'Polled' is the technical breeding term for animals genetically born without horns — you will find it in agricultural catalogues and breed standards ('polled Hereford'). 'Unhorned' is a general, less common adjective that can describe any animal without horns, whether naturally or by removal. 'Dehorned' specifically means the horns were surgically or chemically removed after birth, so it implies a procedure took place. For everyday use, 'hornless' is the clearest choice; use 'polled' when discussing genetics or breeds, 'dehorned' when discussing animal management practices.
Etymology
Formed from the noun 'horn' (the hard pointed growth on the heads of some animals, from Old English 'horn') plus the suffix '-less' (meaning 'without'). The word has been used since the 13th century, mainly in descriptions of livestock.