Complementation test; trans test
Introduction of two mutant chromosomes into the same cell to determine whether the mutants are alleles of the same gene.  If the mutations are non-allelic, the genotype will be m1 +/+ M2 and the phenotype will be wild-type (normal), because each chromosome "covers" for the other.  In contrast, if they are allelic, the mutant phenotype will result.

Composite
A material brought about by combining materials differing in composition or form on a macroscale for the purpose of obtaining specific characteristics and properties.  The constituents retain their identity such that they can be physically identified and they exhibit an interface between one another.

Composite transposon
A transposable element formed when two identical or nearly identical transposons insert on either side of a non-transposable segment of DNA, such as the bacterial transposon Tn5.

Composting
The controlled aerobic degradation of organic wastes into a material which can be used for landscaping, landfill cover or soil conditioning.

Compression settling
Settling which occurs in the lower reaches of clarifiers where particle concentrations are highest. Particles can settle only by compressing the mass of particles below.

Concatemer
A DNA segment made up of repeated sequences linked end to end.

Concordance
Identity of matched pairs or groups for a given trait; such as sibs expressing the same trait.