or Heterogena, literally imports something of a different nature, or that consists of parts of different or dissimilar kinds; in opposition to homogeneous. The word is Greek; formed of ἑτερός, "different," and γένος, "kind;" q.d. composed of different kinds of parts.

Heterogeneous Light, is by Sir Isaac Newton said to be that which consists of rays of different degrees of refrangibility. Thus the common light of the sun or clouds is heterogeneous, being a mixture of all sorts of rays.

Heterogeneous Nouns, one of the three variations in irregular nouns; or such as are of one gender in the singular number, and of another in the plural.—Heterogeneous, under which are comprehended mixed nouns, are six-fold. 1. Those which are of the masculine gender in the singular number, and neuter in the plural; as, ἡ τάρταρος, ἡ τάρταρος. 2. Those which are masculine in the singular number, but masculine and neuter in the plural; as, ἡ τάρταρος, ἡ τάρταρος. 3. Such as are feminine in the singular number, but neuter in the plural; as, ἡ τάρταρος, ἡ τάρταρος. 4. Such nouns as are neuter in the singular number, but masculine in the plural; as, ἡ τάρταρος, ἡ τάρταρος. 5. Such as are neuter in the singular, but neuter and masculine in the plural; as, ἡ τάρταρος, ἡ τάρταρος. And, 6. Such as are neuter in the singular, but feminine in the plural number; as, ἡ τάρταρος, ἡ τάρταρος.

Heterogeneous Quantities, are those which are of such different kind and consideration, as that one of them, taken any number of times, never equals or exceeds the other.

Heterogeneous Surds, are such as have different radical signs; as, √aa, and √bb; √9, and √19.

Heteroscilii, in geography, a term of relation, denoting such inhabitants of the earth as have their shadows falling but one way, as those who live between the tropics and polar circles; whose shades at noon in north latitude are always to the northward, and in south latitude to the southward.