The Collaborative International Dictionary of English v.0.48:
Grenade \Gre*nade"\, n. [F. grenade a pomegranate, a grenade, or
Sp. granada; orig., filled with seeds. So called from the
resemblance of its shape to a pomegranate. See Carnet,
Grain a kernel, and cf. Pomegranate.] (Min.)
A hollow ball or shell of iron filled with powder of other
explosive, ignited by means of a fuse, and thrown from the
hand among enemies.
(a) A small grenade of iron or glass, usually about two and a
half inches in diameter, to be thrown from the hand into
the head of a sap, trenches, covered way, or upon
besiegers mounting a breach.
(b) A portable fire extinguisher consisting of a glass bottle
containing water and gas. It is thrown into the flames.
Called also fire grenade.
Rampart grenades, grenades of various sizes, which, when
used, are rolled over the pararapet in a trough.