Noah Webster
Variable
VA'RIABLE, adjective
1. That may vary or alter; capable of alteration in any manner; changeable; as variable winds or seasons; variable colors.
2. Susceptible of change; liable to change; mutable; fickle; unsteady; inconstant; as, the affections of men are variable; passions are variable
His heart I know, how variable and vain.
3. In mathematics, subject to continual increase or decrease; in opposition to constant, retaining the same value.
VA'RIABLE, noun In mathematics, a quantity which is in a state of continual increase or decrease. The indefinitely small quantity by which a variable is continually increased or diminished, is called its differential, and the method of finding these quantities, the differential calculus.