Set Difference
The set difference 
is defined by
The same symbol is also used for Quotient Groups.
- Irreducible Semiperfect Number
- Irreducible Tensor
- Irredundant Ramsey Number
- Irreflexive
- Irregular Pair
- Irregular Prime
- Irregular Singularity
- Irrotational Field
- Isarithm
- ISBN
- I-Signature
- Island
- Isobaric Polynomial
- Isochronous Curve
- Isoclinal
- Isocline
- Isoclinic Groups
- Isodynamic Points
- Isoenergetic Nondegeneracy
- Isogonal Conjugate
- Isogonal Line
- Isogonic Centers
- Isograph
- Isohedral Tiling
- Isohedron