Facts in Much Ado About Nothing

To be on the "windy side of care" means to be out of care's way, or out of danger. This is a nautical allusion: the windy side is the windward side, which gives a ship enough wind to maneuver out of danger.

Hero refers to hawks (haggards) that, like Beatrice, are almost impossible to domesticate.

During Shakespeare’s time, illnesses were thought to be caused by fluids or parasites. According to Humorism, a system of medicine considered to have been developed by the ancient Greeks, there were four different “humour[s]” (bodily fluids) that determined a person’s temperament and physical health: blood, yellow bile, black bile, and phlegm. It was believed that an imbalance of these humours would result in illness. Being in love (especially unrequited love) was thought to produce an overabundance of black bile, which was associated with melancholy.

People who are buried with the face upwards have died an acceptable Christian death, as distinguished from suicides, who are buried with the faces downwards.

“Light o’ love” is the name of an old dance tune. During Shakespeare’s time, “Light o’ love” was also used as an expression for the inconstant nature of love, or specifically as a noun to describe a woman who was fickle with love.

The title Goodman (also, yeoman) is for a man just below the level of gentlemen. Think of a property and business owner or artisan (like Shakespeare's father, a glove maker) in the middle class.

A friar is a member of any certain religious orders, especially the four mendicant orders: the Augustinians, Dominicans, Franciscans, and Carmelites.

As usual, Dogberry has things backward—usually, charges are brought on the basis of suspicion ("to be thought so shortly") and then the charges are proved.

As with his earlier use of boy to refer to Claudio, Benedick refers to Claudio's inability to grow a beard, implying that he is not manly enough.  In Shakespeare's time, most men wore beards, and boys looked forward to the time they could grow their first beard.

Duels are conducted very formally—when the challenge is issued, it must be formally accepted by the challenged party. 

A buckler was a small fencing shield that consisted of a round piece of wood with a small raised circle of iron. It was meant to catch the tip of one’s opponent’s sword. Beatrice uses this reference to make a bawdy joke that refers to female genitalia.

This is a saying that comes from fencing, meaning “I give up” or “I yield.” Bucklers were small round shields used for protection against a fencing sword.

The Elizabethan sonnet tradition evolved out of Petrarch's Italian sonnet. These were 14-line poems written in iambic pentameter in which a speaker would talk about her desire for an unattainable love object. Sonnet sequences, a collection of 150 sonnets that slowly told an unrequited love story, became popular in the 1580s with Philip Sidney’s Astrophil and Stella. However, because of this popularity, many imitation writers were drawn to the form. This changed the popular opinion of sonnets as a high form of literature to something more common and formulaic, much like some modern day pop songs.

This is a sarcastic reference to knights who, instead of fighting, spent their time with the ladies, presumably kneeling on carpets while they sang their ladies' praises.  The phrase is synonymous with "ladies man."

When fencers practice, they use a foil with a blunt tip so as not to injure their opponents, so Margaret is telling Benedick that his wit is dull.