(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 foodingredient; they are frequently stewed with sugar and made into jam or used in crumbles, pies, etc.
The dried rhizome and roots of Rheum palmatum (Chinese rhubarb) or Rheum officinale (Tibetan rhubarb), from China, used as a laxative and purgative.
Of the colour of rhubarb: either brownish-yellow (the colour of rhubarb rhizomes and roots used for medicinal purposes), or pale red (often the colour of the leafstalks of common rhubarb).
(US, originally baseball, countable) An excited, angry exchange of words, especially at a sporting event.
(US, originally baseball, by extension, countable) A brawl.
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.
(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.