Caithness uses the word "medicine" to mean a "doctor" who will cure the "weal," or commonwealth. This refers directly to Malcolm who is also referred to as a "sovereign flower" by Lennox.

Since clothes often symbolize titles in this play, this simile illustrates how Macbeth is unfit to rule. The clothes and title of king hang about him because he is too small and unfit to wear them.

When nobles and others swear allegiance to a king, their loyalty is equated to good faith—that they will protect and honor their sovereign and not cross or challenge his interests. Since Macbeth murdered the one he swore allegiance to, he breached, or broke, his oath of loyalty.

Angus states that mutiny and the tyrannical rule of Macbeth have revealed him for what he is. This descriptive line reveals that the nobles all know that Macbeth committed the crimes against Duncan and Banquo because they stick to his hands—he cannot pin their murders on others anymore.

Caithness uses this metaphor to describe Macbeth losing control of his forces. "Buckle" here refers to the rule or control he has over his party, and since he cannot buckle his metaphorical belt, he cannot possible rule over his discontented army.

While a modern audience understands "protest" as negatively denouncing another action, in this context Lennox says the youths are "claiming" or "demanding" to call themselves men by joining the campaign against Macbeth.

In Holinshed's Chronicles, which Shakespeare used for many characters in this and other plays, Siward is described as Duncan's father-in-law, which would make Siward Malcolm's grandfather. The choice of "uncle" here could represent a more familial term of endearment.

While we haven't met these characters yet, their presence with Lennox and the discussion they have reveal them to be Scottish nobles joining the revolt against Macbeth's rule.

In this context, "dear" has a connotation of closeness; that is, the reasons for their revenge are personal. Mentieth quite descriptively says that these causes for their revenge are so strong that they would even raise a dead man to fight for their cause.

Shakespeare uses an abstract, plural noun to show how multiple people are affected by the quality or feeling that the noun denotes. In this instance, even though they have a common target for their revenge, they are all affected differently and have different motivations for pursuing their revenge.