Facts in Macbeth
The western isles refers to the Hebrides, which are off the western coast of Scotland. The sergeant states that Celtic soldiers joined Macdonwald's forces: Kerns were lightly armed soldiers from Ireland and Scotland who carried wooden shields and a sword of bow; the gallowglass were mercenaries and armored warriors known for their strength and size.
Aleppo is a city in Syria and was under the control of the Ottoman Empire when Shakespeare wrote Macbeth. During the Middle Ages it was a center of trade and Christianity in the Middle East.
When talking about himself, Duncan uses the plural pronoun "we" in this section. This is known as the royal "we" and refers to a single person who holds a high office, such as a king or religious leader, and speaks for the well-being of many others.
In a scene meant for comic relief, the Porter tells Macduff how too much alcohol has deceptive effects on people. Following this line, he uses contrasting expressions to make a joke to the audience about how drink can make a man sexually aroused but leave him unable to physically perform.
Continuing with his hell-gate fantasy, the Porter imagines the next person he would encounter. In this case, Shakespeare alludes to the Gunpowder Plot of 1605 in English history, when conspirators sought to overthrow the British monarchy. The “equivocator” likely alludes to a Jesuit priest named Father Henry Garnet, known as the great "equivocator" because of his ability to use unclear language to deceive others. He was eventually hanged for his role in the event.
Beelzebub is a high-ranking fallen angel who served Satan in Milton's Paradise Lost. In common usage, the name Beelzebub can be used synonymously or as a nickname for the Devil or Satan.
Colmekill refers to a monastery on the island of Iona off the west coast of Scotland. It is named after St. Columba, who converted Scotland to Christianity. Since this monastery has a reputation for holiness, it became a favorite burial place for Scottish kings: forty-eight kings are reportedly buried there. Interestingly, the historical Macbeth and Duncan were interred here.
Scone is an ancient, royal city in Scotland nor far from the present-day town of Perth. It contained a throne, on which Scottish kings, such as Macbeth, were crowned.
The word score can mean a a group of twenty things. It is commonly used in combination with a number, as in this selection, and if it lacks another noun stating what the score consists of, then it typically refers to years. The Old Man is saying sixty and ten years ago.
These two types of dogs are both older, historical names and references. "Shoughs" refers to a kind of lap-dog, believed to have been originally from Iceland. "Water-rugs" refers to a type of water dog that had a rough or shaggy coat (possibly a kind of poodle).
Parricide refers to the act of murdering one's father, mother, or a close relative. A more specific word choice would be patricide which specifically refers to the act of murdering one's father.
A "sennet" is a set of notes played on a brass instrument, such as a trumpet or cornet, that was used in stage directions of Elizabethan plays as a signal for ceremonial entrances or exits of certain actors--in this case, King Macbeth.
The identity of the Third Murderer is a point for much speculation, with some even suggesting that Macbeth himself is the Third Murderer in disguise. However, this is highly unlikely, given how he knows nothing of what transpires in this scene when the murderers later tell him the results.
Acheron is one of the rivers in Hades according to classical Greek mythology. Since it is associated with the underworld, then it has connections to the Christian concept of hell, evil, and the devil. The witches have been portrayed as associated with the devil, so Hecate suggesting they all meet at "the pit of Acheron" reinforces this notion that they are wholly evil.
This scene is generally considered incongruous with the rest of the play, and the part of Hecate is omitted from some modern representations. Shakespearean scholar A. C. Bradley suggests that Thomas Middleton potentially included this scene at a later date, based on, for example, the fact that the two songs in the sage directions here have been found in Middleton's The Witch. Considering this, Act III Scene v may be skipped in its entirety and the play will easily continue without any of the information here.
Known as Edward the Confessor, he was King of England from 1042 to 1066, the last of the Anglo-Saxon kings of England, and well known for being pious and saintly without becoming a martyr.
This word, operating as an interjection here, is a now archaic way of expressing surprise, outrage, shock, etc., or of emphasizing someone's words. Etymologically, it is related to the the name Mary, for the Virgin Mary who was the mother of Jesus.
These eight kings represent the eight rulers of the Scottish house of Stuart (Stewart). starting with Robert II to James VI. According to the English chronicler Raphael Holinshed, the Royal Stuarts traced their line of ancestry back to Banquo.
The glass that the eighth holds is not a container for liquid; it is a magical looking glass that one could see the future within. The eighth king is likely James VI of Scotland who was ruling England King James I when Macbeth was written. Shakespeare's inclusion here likely represents a compliment and praise for the king and the future of his heirs.
Macbeth's exclamation alludes to a belief during the reign of James I of England (the Jacobean era) that a thunderclap ("crack") announced the coming of Doomsday ("doom). Essentially, Macbeth thinks that Banquo's children and heirs will reign for a very long time.
As the witches brew a potion in the cauldron, they repeat this chant as a kind of evil spell. Interestingly, Shakespeare uses tetrameter (four beats per line) instead of iambic pentameter for the witches spell. This incantation, the cauldron, and the evil atmosphere all credit Shakespeare with the creation of the Western conception of a typical witch.
A cauldron is simply a large kettle or boiler that can be used for cooking or heating liquids. However, in Western culture cauldron's have strongly become associated with witchcraft with this scene being one of the first and most memorable instances of witches brewing a potion in a cauldron.
The disease is called scrofula, a form of tuberculosis, and was known as the "king's evil" because the English Kings were believed to be able to cure it by putting their hands on the victim. This ability to cure this disease is believed to have originated with Edward the Confessor, the current King of England in Macbeth.
While this word in general use refers to the lands of the Arabian peninsula, in poetry it often has connotations of a mysterious place known for many exotic items, such as spices and perfumes.