Invariant

Invariant may have meanings

Invariant (computer science), an expression whose value doesn't change during program execution
In computer science, a type in overriding that is neither covariant nor contravariant
Invariant (mathematics), something unaltered by a transformation
Invariant (music)
Invariant (physics) a quantity conserved by system symmetry
Invariant representation (cognitive science), the form or essence of something, an abstraction from particulars
The Invariant Society, the undergraduate mathematical society of Oxford University