(grammar) A noun in which number is not marked; that is, a noun which does not change form in the plural, such as, in English, fish and series.

(law) Something that must not be removed or modified during redistribution. / (mathematics) A section that will not vary through changing state.

plural of Lorentz invariant

plural of loop invariant

plural of Zeuthen-Segre invariant

(geometry) A certain invariant of complex projective surfaces.

plural of Gromov-Witten invariant

(mathematics) A rational number that, in certain situations, counts pseudoholomorphic curves meeting prescribed conditions in a given symplectic manifold. They have applications in string theory.

plural of Donaldson-Thomas invariant

(algebraic geometry) Given a compact moduli space of sheaves on a Calabi-Yau threefold, its Donaldson-Thomas invariant is the virtual number of its points, i.e., the integral of the cohomology class 1 against the virtual fundamental class.