- isospectrality
- isospectral manifolds
- isospin invariance
- isostrophic loop
- isostrophic quasigroup
- isostrophy
- isosurface
- isothermal
- isothermal-asymptotic surface
- isothermal-conjugate net
- isothermal-conjugate parameters
- isothermal-conjugate representation
- isothermal coordinate
- isothermal form
- isothermal jump
- isothermal lines
- isothermal net
- isothermal parameter
- isothermal parameter curve
- isothermal parameterization
- isothermal surface
- isothermal system of curves
- isothermic
- isotomic conjugate (= isotomic conjugate point)
- isotomic cubic