Monologue - refers to a speech by one person in a drama, a form of entertainment by a single speaker, or an extended part of the text of a play uttered by an actor.
The term is taken directly from the Greek monologos, meaning “speaking alone.”
An example is Macbeth’s questioning of his own sanity in Shakespeare’s Macbeth:
Is this a dagger which I see before me,
The handle toward my hand? Come, let me clutch thee!
I have thee not, and yet I see thee still.
Art thou not, fatal vision, sensible
To feeling as to sight? or art thou but
A dagger of the mind, a false creation,
Proceeding from the heat-oppressed brain?
Act II, scene i : lines 42 – 48