Africa 
China 
Japan 
MENA 
- Irreducible representations
- Irregular bones
- Irregular matrix
- Irreversibility
- Irreversible electroporation
- Irrigation
- Irrigation management
- Irrigation scheduling
- Irritability
- Irritant contact dermatitis
- Irritation
- Irrotational
- Irving-Williams series
- Is
- Isabelle
- Isasmelt
- Isatin
- Ischemia
- Ischemic cardiomyopathy
- Ischemic optic neuropathy
- Ischemic preconditioning
- Ischium
- Isenthalpic
- Isenthalpic process
- Isentropic
- Isentropic process
- Isethionic acid
- Ishihara test
- Ishikawa diagrams
- Isight
- Ising model
- Islanding
- Islands
- Islands of automation
- Isoamyl acetate
- Isoamyl alcohol
- Isoamylase
- Isobaric
- Isobaric process
- Isobaric tag for relative and absolute quantitation
- Isobars
- Isobutane
- Isobutyl acetate
- Isobutylene
- Isobutyraldehyde
- Isobutyric acid
- Isobutyronitrile
- Isochoric
- Isochoric process
- Isochronous
- Isocitrate dehydrogenase
- Isocitrate lyase
- Isocline
- Isocyanate
- Isocyanide
- Isodesmosine
- Isoelectric focusing
- Isoelectric point
- Isoelectronic
- Isoflavones
- Isoflurane
- Isoforms
- Isogeometric analysis
- Isoionic point
- Isolated brain
- Isolated ground
- Isolated lung perfusion
- Isolated point
- Isolated singularity
- Isolated system
- Isolates
- Isolation
- Isolation amplifier
- Isolation forest
- Isolation transformer
- Isolation valves
- Isolators
- Isomaltase
- Isomaltose
- Isomap
- Isomerases
- Isomerization
- Isomers
- Isometric
- Isometric projection
- Isometry
- Isomorphism
- Isomorphism class
- Isomorphous
- Isoniazid
- Isooctane
- Isopach map
- Isopentane
- Isopeptide bonds
- Isoperimetric inequality
- Isophorone
- Isophorone diamine
- Isophorone diisocyanate
- Isophthalic acid
- Isopimaric acid
- Isoprene
- Isopropyl
- Isopropyl acetate
- Isopropyl alcohol
- Isopropyl myristate
- Isopropyl palmitate
- Isopropylamine
- Isoprostane
- Isoquants
- Isoquinoline
- Isosceles right triangle
- Isosceles trapezoid
- Isoseismal map
- Isosorbide
- Isospectral
- Isostasy
- Isostructural
- Isosurface
- Isothermal
- Isothermal process
- Isothermal transformation
- Isothiazolinones
- Isothiocyanates
- Isotonic
- Isotonic contractions
- Isotope analysis
- Isotope fractionation
- Isotope hydrology
- Isotope ratio
- Isotope separation
- Isotopes
- Isotopes of helium
- Isotopes of iodine
- Isotopes of lithium
- Isotopes of oxygen
- Isotopes of plutonium
- Isotopes of sulfur
- Isotopes of thorium
- Isotopic labeling
- Isotopomers
- Isotropic
- Isotropic antenna
- Isotropic etching
- Isotropic radiation
- Isotropic radiator
- Isotropic solid
- Isovaleraldehyde
- Isoxazole
- Isozymes
- Issue-based information system