The Collaborative International Dictionary of English v.0.48:

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]

The Collaborative International Dictionary of English v.0.48:

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

WordNet (r) 3.0 (2006):

poniard
    n 1: a dagger with a slender blade [syn: poniard, bodkin]
    v 1: stab with a poniard