noun

• (countable, uncountable) Any plant of the family Poaceae, characterized by leaves that arise from nodes in the stem and leaf bases that wrap around the stem, especially those grown as ground cover rather than for grain.
  "Thou turnest man to destruction: and sayest, Returne yee children of men. / For a thousand yeeres in thy sight are but as yesterday when it is past: and as a watch in the night. / Thou carriest them away as with a flood, they are as a sleepe: in the morning they are like grasse which groweth vp. / In the morning it flourisheth, and groweth vp: in the euening it is cut downe, and withereth."
• (countable) Various plants not in family Poaceae that resemble grasses.
• (uncountable) A lawn.
• (uncountable) The outside world, especially in the phrase "touch grass".

verb

• (transitive) To lay out on the grass; to knock down (an opponent etc.).
  "The Chicken himself attributed this punishment to his having had the misfortune to get into Chancery early in the proceedings, when he was severely fibbed by the Larkey one, and heavily grassed."
• (transitive or intransitive, slang) To act as a grass or informer, to betray; to report on (criminals etc) to the authorities.
  ""Grassed on me he did," I said morosely. (Note: Grass is English thief slang for inform.)^([sic])"
• (transitive) To cover with grass or with turf.
• (transitive) To feed with grass.