1. The act of condensing; the state of being condensed.
2. The result of being made more compact or dense.
3. A reduction of a book, speech, statement, or the like, to a shorter or terser form; abridgment.
4. A condensed form: "Did you read the whole book or just a condensation?"
5. The act or process of reducing a gas or vapor to a liquid or solid form.
6. In chemistry, a reaction between two or more organic molecules leading to the formation of a larger molecule and the elimination of a simple molecule such as water or alcohol.
7. The process by which atmospheric water vapor liquefies to form fog, clouds, or the like, or solidifies to form snow or hail.
8. The representation of two or more ideas, memories, feelings, or impulses by one word or image, as in a person's humor, accidental slips, or dreams.
9. The relative amount by which the density of an elastic medium varies from its average value as a sound wave passes through it.
10. A reaction of two or more organic chemicals, one of the products of which is water, ammonia, or a simple alcohol.
11. A process by which water vapor changes to dew, fog, or clouds; brought about either by the cooling of air to its dew point or the addition of enough water vapor to bring the mixture to the point of saturation.

The transformation of water in the air from a vapor phase to dew, fog, or to a cloud: Early the next morning Stella could see the moisture on the blades of grass on the lawn due to atmospheric condensation.