noun

• (often attributive) The leafstalks of common rhubarb or garden rhubarb (usually known as Rheum × hybridum), which are long, fleshy, often pale red, and with a tart taste, used as a food ingredient; they are frequently stewed with sugar and made into jam or used in crumbles, pies, etc.
  "Rhubarb Tarts. Take the ſtalks off the rhubarb that grows in the garden, peel the ſkin off, and cut them the ſize of a gooſeberry, put them into china or earthen-ware patty-pans, with ſugar over them, and put on a paſte either puff or tart, ice them, and bake them the ſame as green gooſeberries, and they will eat like them."
• (British, military, aviation, historical) A Royal Air Force World War II code name for operations by aircraft (fighters and fighter-bombers) involving low-level flight to seek opportunistic targets.
  "On 13 December 1942, Squadron Leader [Brian] Lane made his first flight from Ludham, a local familiarisation flight. That afternoon, he led a section of Spitfires low over the North Sea on a ‘Rhubarb’, a low-level sweep over the Dutch coast, looking for targets of opportunity."
• (Saskatchewan, Ottawa Valley) A ditch alongside a road or highway.
  "Driving home yesterday, I almost hit the rhubarb."

verb

• (British, military, aviation) Of fighter aircraft: to fire at a target opportunistically.

noun

• (originally theater, uncountable) General background noise caused by several simultaneous indecipherable conversations, which is created in films, stage plays, etc., by actors repeating the word rhubarb; hence, such noise in other settings.
  "It [the film The Picnic] wasn't actually a silent film; there were sound effects, but the dialogue was a rhubarb-ish series of grunts and mutters."
• (UK, uncountable, by extension) Nonsense; false utterance.
  "MADAME JOURDAIN: No, it’s all complete rhubarb. MONSIEUR JOURDAIN: Dara dara bastonnara! He begins to dance and chant. MADAME JOURDAIN: Don’t think that’s going to make things any clearer."
• (US, originally baseball, countable) An excited, angry exchange of words, especially at a sporting event.
  "Out in the bullpen, Chip Hilton and Soapy Smith had stopped throwing to watch the argument—what ballplayers call a "rhubarb.""
• (US, originally baseball, by extension, countable) A brawl.
  "But damned if it don't seem like killin' him would stir up an even bigger political rhubarb. I mean, it ain't like nobody'd have to be told who did it."

verb

• (intransitive, originally theater) Of an actor in a film, stage play, etc.: to repeat the word rhubarb to create the sound of indistinct conversation; hence, to converse indistinctly, to mumble.
  "At Rick's side our local Liberal Party Chairman is smacking his yeoman's paws together and rhubarbing ecstatically in Rick's ear."
• (transitive) To articulate indistinctly or mumble (words or phrases); to say inconsequential or vague things because one does not know what to say, or to stall for time.
  "Ordinarily this group of egos rhubarbed about matters as trivial as whose turn it was to order the next round, but tonight they were united in their project, and while men were killing one another all over the world, a strange peace had broken out among America's swim coaches."