I vaguely remember that a joint probability density $f(x,y)$ can be marginalized into a function of one variable $\int f(x,y)dx=F(y)$.
Is there a corresponding word for "collapsing" a function $f(x,y)$ of two variables into a function $g(y)=f(x,y)$ of one variable by turning one of the variables into a known constant?