In Act I scene 2 of As You Like It, what does Rosalind mean by the phrase "rib-breaking"?
The phrase "rib-breaking" here refers to the wrestling match that is going to happen between Orlando and Charles. Le Beau has already told Rosalind how Charles has triumphed over three wrestlers by breaking their ribs during the wrestling match. Touchstone is of course typically cynical about the kind of "sport" that such barbarity represents, and Rosalind picks up on the way in which this "rib-breaking" is actually a savage activity when she says:
But is there any else longs to see this broken music in his sides? Is there yet another dotes upon rib-breaking? Shall we see this wresting, cousin?
Note the use of the word "dotes" here to imply folly and the ridiculous way in which such violence constitutes sport and entertainment for some. Thus the phrase "rib-breaking" refers to the wrestling match that is going to occur between Charles and Orlando and also it implies the violence that Orlando is going to suffer.
The eldest of the three wrestled with Charles, the duke's
wrestler; which Charles in a moment threw him, and broke three of
his ribs, that there is little hope of life in him: so he served
the second, and so the third. Yonder they lie; the poor old man,
their father, making such pitiful dole over them that all the
beholders take his part with weeping.
In connection with this reporting made by Le Beau in As You Like It, act 1 scene 2, that Rosalind used the phrase:
But is there any else longs to see this broken music
in his sides? is there yet another dotes upon rib-breaking?
Shall we see this wrestling, cousin?
Orlando, youngest son of the late Sir Rowland de Boys, complains to Adam, an elderly family servant, that his brother Oliver has unfairly withheld his late father's inheritance and prevented him from being educated as a gentleman. Oliver enters and a heated argument ensues. When Oliver learns that his brother plans to challenge Duke Frederick's wrestler,Charles, he plots with Charles to break his brother's neck during the match.
The next day when Duke Frederick's daughter Celia, his niece Rosalind, and the Fool, Touchstone, are in conversation, Le Beau enters to report that a wrestling match is going to take place in which Charles, who has subdued his first three opponents by breaking their ribs, shall face Orlando. It is in this context that Rosalind mentioned the phrase.