The property of having one dimension WordNet 3.0 & Open English WordNet

In mathematics, the term linear is used in two distinct senses for two different properties: linearity of a function ; linearity of a polynomial. Wikipedia

Property of mathematical operator such that f = a⋅f + b⋅f Wikidata

property of mathematical operator such that f(a⋅x + b⋅y) = a⋅f(x) + b⋅f(y) Wikidata

The property of being linear. OmegaWiki

A relationship between several quantities which can be considered as proportional and expressed in terms of linear algebra, or any mathematical property of a relationship, operation or function that is analogous to such proportionality, satisfying additivity and homogeneity. Wiktionary

Proportionality or a mathematical property analogous to it. Wiktionary (translation)