Adjective
Capable of being changed or converted; as, invertible sugar.
Incapable of being turned or changed.
Source: Webster's dictionaryA function is invertible if and only if it is a bijection. Source: Internet
A matrix that is not invertible has condition number equal to infinity. Source: Internet
An element with an inverse element only on one side is left invertible, resp. right invertible. Source: Internet
An affine transformation is invertible if and only if is invertible. Source: Internet
A groupoid can be seen as a: * Group with a partial function replacing the binary operation ; * Category in which every morphism is invertible. Source: Internet
For ψ to be a wavelet for the continuous wavelet transform (see there for exact statement), the mother wavelet must satisfy an admissibility criterion (loosely speaking, a kind of half-differentiability) in order to get a stably invertible transform. Source: Internet