A story, character, place, or event is used to convey a hidden meaning, typically moral or political, about real-world events or issues (e.g. Duncan's death is an allegory for the risks of killing your king)
Words or phrases that have a double meaning and is deliberately ambiguous, especially when one of the meanings is risqué. (For example: In Elizabethan England, the use of the word "die" referred to both death and orgasm)
A literary technique that places two opposing words, phrases or events side by side, often for the main purpose of comparing or contrasting them. (For example - "Here is much to do with hate, but more to do with love.")
A form of paradox that combines a pair of contrasting terms into a single, sometimes unique expression. (For example - When Juliet says "O happy dagger")