quaking grassEnglishOxford New American Dictionaryquaking grass /kwākiNG ɡras, kweɪkɪŋ ɡræs/ ▸ noun a slender-stalked grass with oval or heart-shaped flower heads which tremble in the wind. Genus Briza, family Gramineae: several species, including B. media, which is sometimes cultivated as an ornamental.