The Collaborative International Dictionary of English v.0.48:
Grate \Grate\, n. [LL. grata, fr. L. crates hurdle; or It.
grata, of the same origin. Sae Crate, Hurdle.]
1. A structure or frame containing parallel or crosed bars,
with interstices; a kind of latticework, such as is used
ia the windows of prisons and cloisters. "A secret grate
of iron bars." --Shak.
2. A frame or bed, or kind of basket, of iron bars, for
holding fuel while burning.
Grate surface (Steam, Boiler) the area of the surface of
the grate upon which the fuel lies in the furnace.