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

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

(mathematics) An ordinary trigonometric function

(retronym, linguistics) Any human language that has evolved naturally in a community, usually in contrast to computer programming languages, to controlled natural languages, and to constructed languages such as Esperanto (although constructed languages are subject to change by natural forces among fluent speakers).

(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

(immunology) A natural killer cell

A food that has been not been processed in any way that alters covalent bonds, and to which no artificial substance has been added.