Collinearity indicates that a set of points are on a single line. Alternative spellings are co-linear or colinear. The version with the double l is typically preferred due to a latin grammatical rule, an example of which is the spelling of attractive, which derives from ad tractare where the d is lost and the consonant doubled. The fusion of cum linea to produce collinear works in a similar way.

Depending on the technical field it may refer to:

In mathematics

• Line (mathematics)
• Linear regression
• Multicollinearity
• colinear map is the dual notion of a linear map in comodule theory.

In engineering

• Collinear antenna array

In biology

• Different elements of a system that are correlated but one is not the cause of the other, for example the genes in a hox cluster activate sequentially in time and in space (anatomical location) according to the order the genes are present in the cluster, which is the main defining feature of this gene cluster.