Knife (envelope)
WordNet
noun
(1) Edge tool used as a cutting instrument; has a pointed blade with a sharp edge and a handle
(2) A weapon with a handle and blade with a sharp point
(3) Any long thin projection that is transient
"Tongues of flame licked at the walls"
"Rifles exploded quick knives of fire into the dark"
verb
(4) Use a knife on
"The victim was knifed to death"