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