- intramolecular bond
- intrinsic spin
- intrinsic temperature
- intrusion tone
- invalid
- invar
- inventory
- inverse magnetostriction
- inversion spectrum
- inviscid flow
- invisible
- ion accelerator
- ion implantation
- ion milling
- ionic charge
- ionic exchanger
- ionic impurity
- ionized gas
- ionosphere
- ionospheric
- ionospheric wave
- iporka
- iris
- iron loss
- irradiated temperature
- irradiation
- irradiator
- irregular fluctuation
- irregular temperature
- irregular ventilation
- irresoluble
- isenthalpic expansion
- isenthalpic line
- isentropic
- isentropic change
- inward
- ion counter
- ionic exchange
- ionization detector
- ionizing agent
- ionizing potential
- IR drop
- iris diaphragm
- irradiance
- irradiated product
- irrefutable
- irregular nebula
- irreversible throttling
- irrotational
- irrotational flow
- isenergetic
- isenergetic flow
- isenthalpic process
- isentropic compression
- isentropic expansion
- isentropic exponent
- isentropic flow
- isentropic line
- isentropic process
- isentropic refrigeration
- Ising model
- isoamplitude
- isobutane
- isocandle
- isochromate
- isochromatic
- isochronism
- isochrous
- isoclinic fringe
- isodiaphere
- isodose
- isoelectronic
- isoelectronic sequence
- isoenergetic
- isoenthalpic
- isoflex
- isogeotherm
- isogonic
- isolation meter
- isolation tester
- isolith
- isolux
- isomeric transition
- isomerisation
- isomerize
- isomery
- isometric line
- isomorphism
- isoorthochromatic
- isopachic fringe
- isopanchromatic
- isophasal
- isophot
- isoseismic
- isostatic pressing
- isostructural
- isotac
- isothermal change
- isothermal compressibility
- isothermal compressor