adjective. Of, relating to, or being a quantity that is either positive or zero.

adjective. (of a quantity) Not negative; either zero or positive

noun. Any value that is not negative.

adjective. either positive or zero

"Now the covariance matrix can be written as where T is the transpose, U is an orthogonal matrix (, I is an identity matrix), D is a diagonal matrix matrix of eigenvalues (nonnegative numbers)."

nonpositive  nonvanishing  nonzero  

plus  

dimensionless  herby  measurable  non-negative  nonzero