dag·ger 
(dăgər)
(dăgər)n.
Idiom: 1. A short pointed weapon with sharp edges.
2. Something that agonizes, torments, or wounds.
3. Printing
a. See obelisk.
b. A double dagger.
look daggers at
To glare at angrily or hatefully.
[Middle English daggere, alteration of Old French dague, from Old Provençal dague or Old Italian daga, both perhaps from Vulgar Latin *dāca (ēnsis), Dacian (knife), from feminine of Latin Dācus.]