'Poniard' definitions:

Definition of 'poniard'

noun

A dagger with a slender blade [syn: poniard, bodkin]

verb

Stab with a poniard

From: GCIDE

Poniard \Pon"iard\, n. [F. poignard (cf. It. pugnale, Sp. pu[~n]al), fr. L. pugio, -onis; probably akin to pugnus fist, or fr. pugnus fist, as held in the fist. See Pugnacious.] A kind of dagger, -- usually a slender one with a triangular or square blade. [1913 Webster]
She speaks poniards, and every word stabs. --Shak. [1913 Webster]

From: GCIDE

Poniard \Pon"iard\, v. t. [imp. & p. p. Poniarded; p. pr. & vb. n. Poniarding.] To pierce with a poniard; to stab. --Cowper. [1913 Webster]