culmen

from The Collaborative International Dictionary of English v.0.48

Culmen \Cul"men\ (k?l"m?n), n. [L., fr. cellere (in comp.) to
   impel; cf. celsus pushed upward, lofty.]
   1. Top; summit; acme. --R. North.
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   2. (Zool.) The dorsal ridge of a bird's bill.
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