Involving two variables, as opposed to many (multivariate), or one (univariate).
Bivariate
See also
Bivariate Normal Distribution, Multivariate, Univariate, VariateExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Bivariate." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/Bivariate.html