What does a yeasty horn-mad canker-blossom mean in Shakespearean language?

Answer 1

I don't know what you think "Shakespearean language" is, but Shakespeare wrote in English. The particular expression you describe is not found in Shakespeare. Nor is the word "yeasty", but it means full of yeast, tasting of yeast, or like something full of yeast. One might talk about yeasty bread or yeasty beer. Figuratively it might mean ebullient, because of the froth and bubbles yeast gives off.

"Canker-blossom" is used only once in Shakespeare, by Hermia talking to Helena "You juggler! You canker-blossom! You thief of love!" Hermia is mad because she thinks Helena has gone behind her back and alienated Lysander's affection, all the while seeming to be Hermia's friend. A canker is a worm; a canker-blossom is a flower that looks pretty but has a worm in its heart. This is a way of calling Helena a two-timer.

"Horn-mad" appears a number of times in Shakespeare, in the plays A Comedy of Errors, The Merry Wives of Windsor and Much Ado about Nothing. In order to understand this expression, you need to know that cuckolds (men whose wives were unfaithful to them) were portrayed as having horns growing on their head. Almost every time you run across this word in an Elizabethan work it has this meaning either primarily or as a connotation. At the same time men at this time were constantly afraid that the women in their lives might cheat on them, and that they would have to suffer the social shame of being a cuckold, of "wearing the horns". Many of Shakespeare's plays (Othello, Cymbeline, The Winter's Tale, The Merry Wives of Windsor, Much Ado About Nothing) deal with totally unfounded accusations of infidelity by husbands against wives.

A man driven insane by jealousy is horn-mad.

A person who is horn-mad is unlikely to be a canker-blossom at the same time. For one thing, the former applies primarily to men, and the latter is more suited to a woman.