noun, plural der·tra [dur-truh] /ˈdɜr trə/. Ornithology.
the extremity of the maxilla of a bird's bill, especially when hooked or differentiated from the rest of the bill, as in pigeons and plovers.
Origin of dertrum
1885–90; < New Latin < Greek dértron membrane, derivative of dérein to skin; compare dérma derma1
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019