1) Changeable 
• (a.) Incapable of being turned or changed. • (a.) Capable of being changed or converted; as, invertible sugar. • (a.) Capable of being inverted or turned.
Said of a matrix if its inverse exists. That is, a matrix A is invertible if there exists another matrix B such that BA=I, where I is the identity matrix.
A function is invertible (with a unique inverse) if the output uniquely determines the input (i.e., it is one-to-one) and the set of legal outputs is equal to the set of legal inputs. The function x^2 is not strictly invertible, while x^3 has an inverse. For operations the definition is slightly looser. While integration and differentiation are con...
In·vert'i·ble adjective [ From Invert .] 1. Capable of being inverted or turned. 2. (Chemistry) Capable of being changed or converted; as, invertible sugar. 
adjective having an additive or multiplicative inverse