n (countable|uncountable) Any plant of the family Poaceae, characterized by leaf|leaves that arise from nodes in the stem, wrap around it for a distance, and leave, especially those grown as ground cover rather than for grain.
n (countable|slang) An informer, police informer; one who betrays a group (of criminals, etc) to the authorities.
n (uncountable|physics) Sharp, closely spaced discontinuity | discontinuities in the trace of a cathode-ray tube, produced by random interference.
v (transitive|or|intransitive|slang) To act as a grass or informer, to betray; to report on (criminals etc) to the authorities.