- In quick tempo
- In rage
- In residence
- In safe custody
- In scale
- In secret
- In series
- In silence
- In situ
- In so far
- In some measure
- In stitches
- In the cart
- In the flesh
- In the fullness of time
- In the middle of
- In the middle of nowhere
- In the negative
- In the neighbouring house
- In the ordinary way
- Incurably
- In the red
- In the twinkling of an eye
- In the vanguard
- In this wise
- In touch with
- In vogue
- In-and-in
- Ina minor key
- Inaccessibility
- Inaction
- Inadmissibility
- Inadvertently
- Inalienable
- Inanimate
- Inanition
- Inanity
- Inapplicable
- Inappropriate
- Inaptness
- Inartistic
- Inaudible
- Inaugurated
- Inauguration
- Incalculable
- Incantatory
- Incapable
- Incapacitate
- Incarnate
- Incarnation
- Incautious
- Incertitude
- Inch
- Inch by inch
- Incharge
- Inchoately
- Incidence
- Incidental
- Incinerate
- Incipient
- Incision
- Incisive
- Incitation
- Incivility
- Inclement
- Incline one's ear
- Inclined
- Inclusion
- Inclusively
- Incoherence
- Incomparability
- Incomplete
- Incompletely
- Incomputable
- Inconsiderable
- Inconsistency
- Inconsitency
- Inconspicuously
- Inconstant
- Incontrovertible
- Incontrovertibly
- Inconvenience
- Inconveniently
- Incorruptible
- Increased respiration
- Increaser
- Incredible
- Incriminate
- Incroyable
- Inculpate
- Incurable
- Incurrent
- Incursion
- Indecency
- Indeclinable
- Indefinite fast
- Indelibility
- Indelicate
- Indented
- Independence