Definition
noun, plural: grasses
(1) Monocotyledonous plant of the family Poaceae (also called Gramineae) characterized by having narrow-blade, sheathing leaves, jointed stems
(2) Any plant of the family Cyperaceae (the sedges) and Juncaceae (the rushes)
(3) A common name for plants with narrow blade-shaped leaves
Supplement
Grasses or also called the graminoids are monocotyledonous plants belonging to the family Poaceae (also called Gramineae). The family Cyperaceae includes the sedges which are also commonly called grasses, such as the many wild marsh and grassland plants.
The rushes plants belonging to the family Juncaceae are also called as grasses. Nevertheless, those plants belonging to the family Poaceae are those that are regarded as the true grasses, such as the cereals, bamboo plants, grassland, and the grasses of lawns. The habitats of the true grasses include wetlands, forests, and tundra.
Word origin: Middle English gras, gres, gers, Old English græs, gærs (grass, blade of grass, herb, young corn, hay, plant; pasture), from Proto-Germanic *grasą (grass)
