To allude is to refer to something indirectly. It is a way of pointing toward something or calling it to mind without explicitly naming it. A pop singer might allude to events in their personal life through abstracted lyrics. Allusions, or references to earlier artistic works, are very common in literature, as in the case of a book title (Brave New World by Aldous Huxley) that borrows language from another work (The Tempest by William Shakespeare).
The adjectives ridiculous and preposterous both describe things that are inconsistent with reason or common sense. True to its root, however, ridiculous implies ridicule or contempt. Preposterous emphasizes foolishness and suggests a topsy-turvy, inverted, or disorderly quality. A preposterous notion or idea, for instance, is so jumbled in its reasoning or so contrary to expected order that it is downright disorienting.
To enhance something is to add to its desirability or to magnify it. To augment something is to make it larger or to increase it. A person might augment or supplement their income by taking a second job; a teacher might augment course curriculum with unique educational experiences. Augment is often used to talk about additions that are made to meet needs, standards, or requirements.