- Il-13
- Il-15
- Il-17
- Il-18
- Il-1α
- Il-21
- Il-22
- Il-23
- Il-3
- Il-33
- Il-5
- Il6r
- Ilastik
- Ileal
- Ileocecal valve
- Ileus
- Iliac crest
- Iliac spine
- Iliac vein
- Iliocostalis
- Iliopsoas
- Iliotibial band
- Ilium
- Ill-posed
- Illegal mining
- Illegal sand mining
- Illinois Basin
- Illite
- Illuminance
- Illumination
- Illuviation
- Ilmenite
- Ilwis
- Image analysis
- Image compression
- Image derivatives
- Image differencing
- Image editing
- Image file formats
- Image fusion
- Image gradient
- Image histogram
- Image impedance
- Image intensifiers
- Image maps
- Image moments
- Image mosaic
- Image noise
- Image order
- Image plane
- Image plate
- Image processing
- Image processors
- Image quality
- Image reconstruction
- Image rectification
- Image registration
- Image resolution
- Image restoration
- Image retrieval
- Image scaling
- Image segmentation
- Image sensor
- Image stabilization
- Image stitching
- Image subtraction
- Image texture
- Image translation
- Image warping
- Image-based modeling and rendering
- Image-guided surgery
- ImageJ
- Imaginary
- Imaginary numbers
- Imaginary unit
- Imaging
- Imaging biomarkers
- Imaging genetics
- Imaging radar
- Imaging spectrometers
- Imatinib
- Imbibition
- Imbricated
- Imbrication
- Imhoff tank
- Imidazolate
- Imidazole
- Imidazolidine
- Imidazolidinyl urea
- Imidazolines
- Imides
- Imines
- Iminium
- Iminodiacetic acid
- Iminosugars
- Immediate early genes
- Immersed Boundary Method
- Immersed tubes
- Immersion cooling
- Immersion foot
- Immersion gold
- Immersive design
- Immobilization
- Immobilized enzymes
- Immune checkpoint
- Immune complexes
- Immune dysregulation
- Immune evasion
- Immune response
- Immune system
- Immune tolerance
- Immunity
- Immunization
- Immunochemistry
- Immunocytochemistry
- Immunoediting
- Immunofluorescence
- Immunogenic cell death
- Immunogenicity
- Immunoglobulin light chains
- Immunoglobulin superfamily
- Immunohistochemistry
- Immunolabeling
- Immunological memory
- Immunology
- Immunomagnetic separation
- Immunomodulation
- Immunoprecipitation
- Immunoreceptor tyrosine-based activation motif
- Immunosenescence
- Immunostaining
- Immunosuppressant
- Immunosuppression
- Immunosuppressive drugs
- Immunotherapy
- Immunotoxins
- Immutable
- Imogolite
- Impact assessment
- Impact craters
- Impact evaluation
- Impact events
- Impact extrusion
- Impact ionization
- Impact pressure
- Impaction
- Impedance
- Impedance analyzer
- Impedance cardiography
- Impedance control