Merriam-Webster's Collegiate Dictionary:
in the same breath
in the street
in the sun
in the tank
in the teeth of
in the wake of
in the way
in the wind
in the wings
in the woodpile
in the works
in the world
in time
in toto
in tow
in trust
in truth
in turn
in unison
in usum delphini
in utero
in utrumque paratus
in vacuo
in vain
in view of
in vino veritas
in virtue of
in vitro
in vitro fertilization
in vivo
in whole
in work
in-
in-and-in
in-between
in-box
in-depth
in-flight
in-group
in-house
in-joke
in-kind
in-law
in-line
in-line engine
in-line skate
in-line skater
in-line skating
in-migrant
in-migrate
in-migration
in-print
in-process
in-service
in-store
in-wrought
in-your-face
in?n?
in?s de castro
inability
inaccessibility
inaccessible
inaccessibly
inaccuracy
inaccurate
inaccurately
inaction
inactivate
inactivation
inactive
inactively
inactivity
inadequacy
inadequate
inadequately
inadequateness
inadmissibility
inadmissible
inadmissibly
inadvertence
inadvertency
inadvertent
inadvertently
inadvisability
inadvisable
inagua
inalienability
inalienable
inalienably
inalterability
inalterable
inalterableness
inalterably
inamorata
inane
inanely
inaneness
