What does "heterogeneous" mean?

Heterogeneous: Differing in kind; having unlike qualities; possessed of different characteristics; dissimilar; -- opposed to homogeneous, and said of two or more connected objects, or of a conglomerate mass, considered in respect to the parts of which it is made up. -- Het`er*o*ge"ne*ous*ly, adv. -- Het`er*o*ge"ne*ous*ness, n. Heterogeneous nouns (Gram.), nouns having different genders in the singular and plural numbers; as, hic locus, of the masculine gender in the singular, and hi loci and hæc loca, both masculine and neuter in the plural; hoc cælum, neuter in the singular; hi cæli, masculine in the plural. -- Heterogeneous quantities (Math.), such quantities as are incapable of being compared together in respect to magnitude, and surfaces and solids. -- Heterogeneous surds (Math.), surds having different radical signs.