A square matrix used to solve simultaneous equations WordNet 3.0 & Open English WordNet

In mathematics, the determinant is a scalar value that is a function of the entries of a square matrix. Wikipedia

Sum of signed terms of n factors from n×n matrix with no two factors sharing row or column Wikidata

A scalar that encodes certain characteristics of a given transformation matrix; the unique scalar function over square matrices which is distributive over matrix multiplication, multilinear in the rows and columns, and takes the value 1 for the unit matrix; abbreviated as: det. Wiktionary

Scalar that encodes certain characteristics of a square matrix. Wiktionary (translation)