(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.

(category theory) A natural transformation whose every component is an isomorphism.

A kind of proof calculus in which logical reasoning is expressed by inference rules closely related to the "natural" way of reasoning, in contrast to axiomatic systems.