(music) A musical grammar which arises spontaneously in a musical culture (as opposed to an artificial grammar).

The study of all living things, especially their origins, evolution and interrelationships. / The study of all natural phenomena: botany, zoology, mineralogy, etc.

(mathematics) The logarithm in base e: either the function that given x returns y such that eʸ = x, or the value of y given by the function.

(biochemistry) Any compound produced naturally by a living organism; especially those compounds that are useful commercially

Any source of wealth that occurs naturally, especially minerals, fossil fuels, timber, etc.

Any science involved in studying phenomena or laws of the physical world: physics, chemistry, biology, astronomy, and so on.

Any natural phenomenon that causes great damage and loss of life. / The emergency situation that is the consequence of such an event.

plural of natural resource

(mathematics) An ordinary trigonometric function

(grammar) The gender that a noun, etc. would be expected to have, based on attributes of the referent, such as physical sex.