~ 1
Brit.
■ noun a thick, heavy stick or bar used as a weapon.
■ verb hit on the head with a ~.
Origin
C19: of unknown origin.
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~ 2 [ kɒʃ , kɒ'seɪtʃ ]
■ abbreviation Mathematics hyperbolic cosine.
Origin
from cos 2 + -h for hyperbolic ; cf. coth .