An ordinary differential equation involves only one independent variable, a partial differential equation involves more than one.
Pains and pleasures give us what mathematicians call the 'independent variable.'
Let x be the independent variable, y the correlative variable which depends upon it.
In other words, mind cannot exist as an "independent variable" in the world; it must always accompany a human brain.
In mathematics, a variable whose value determines the value of other variables. For example, in the formula for the area of a circle, A = πr2, r is the independent variable, as its value determines the value of the area (A). Compare dependent variable.