Definition of natural disaster : a sudden and terrible event in nature (such as a hurricane, tornado, or flood) that usually results in serious damage and many deaths The earthquake was one of the worst natural disasters of this century.
Synthesis, Chemical. the planned production of complex compounds from simpler compounds based on a knowledge of the reactantsâ chemical structure and reactivity. Chemical synthesis usually implies a sequence of several chemical processes (steps). In the early period in the development of chemistry, chemical synthesis was carried out mainly for inorganic compounds and was fortuitous in nature.
semÂ·iÂ·synÂ·thetÂ·ic. Describing the process of synthesizing a particular chemical using a naturally occurring chemical as a starting material, thus obviating part of a total synthesis, for example, the conversion of cholesterol (obtained from a natural source) into a corticosteroid.