The Collaborative International Dictionary of English v.0.48:

Dagger \Dag"ger\ (-g[~e]r), n. [Cf. OE. daggen to pierce, F.
   daguer. See Dag a dagger.]
   1. A short weapon used for stabbing. This is the general
      term: cf. Poniard, Stiletto, Bowie knife, Dirk,
      Misericorde, Anlace.
      [1913 Webster]

   2. (Print.) A mark of reference in the form of a dagger
      [[dagger]]. It is the second in order when more than one
      reference occurs on a page; -- called also obelisk.
      [1913 Webster]

   Dagger moth (Zool.), any moth of the genus Apatalea. The
      larv[ae] are often destructive to the foliage of fruit
      trees, etc.

   Dagger of lath, the wooden weapon given to the Vice in the
      old Moralities. --Shak.

   Double dagger, a mark of reference [[dag]] which comes next
      in order after the dagger.

   To look daggers, or To speak daggers, to look or speak
      fiercely or reproachfully.
      [1913 Webster]