1. elevation especially above sea level or above the earth's surface

- the altitude gave her a headache

Similar word(s): height

Definition categories: attribute, elevation

2. the perpendicular distance from the base of a geometric figure to the opposite vertex (or side if parallel)

Definition categories: shape, distance, length

3. angular distance above the horizon (especially of a celestial object)

Similar word(s): elevation

Definition categories: link

Sentences with altitude as a noun:

- As the altitude increases, the temperature gets lower, so remember to bring warm clothes to the mountains.

- The perpendicular height of a triangle is known as its altitude.