invariant

1. N an entity, quantity, etc, that is unaltered by a particular transformation of coordinates 不变式; 不变量[maths]

a point in space, rather than its coordinates, is an invariant

2. ADJ (of a relationship or a property of a function, configuration, or equation) unaltered by a particular transformation of coordinates (函数，配置或等式的关系或属性)恒定的[maths]