dertrum Zool.
(ˈdɜːtrəm)
Also dertron.
[mod.L., ad. Gr. δέρτρον beak.]
The extremity of the upper bill of a bird when in any way distinguished from the rest of the beak.
| 1889 in Cent. Dict. 1893 A. Newton Dict. Birds i. 33 Various parts of the rostrum have received special names: culmen, the dorsal ridge of the upper bill; apex or tip; dertrum, in which it often terminates. 1959 Van Tyne & Berger Fund. Ornith. 566 Dertrum. Extremity of the upper mandible (maxilla); the hook of the bill. 1964 G. R. Mountfort in A. L. Thomson New Dict. Birds 93/1 Upper mandible... may be divided into the culmen, or dorsal ridge from the tip (dertrum) of the bill to the forehead, and the upper mandibular tomia, or lateral cutting edges. |