General:
* inaccurate
* inactive
* incomplete
* indefinite
* independent
* indirect
* inefficient
* inequality
* inevitable
* informal
* inhabit
* inhale
* initial
* injure
* inside
* insincere
* inspect
* install
* instead
* insufficient
* intact
* intense
* interact
* interest
* interval
* introduce
* invent
* invest
* invisible
* invite
More specific:
* inappropriate
* inaccessible
* inadvisable
* inanimate
* inbound
* incense
* inception
* incite
* incognito
* incoherent
* income
* incorporate
* increase
* incumbent
* indeed
* indent
* indication
* indigenous
* indispensable
* induce
* indulge
* infamous
* inference
* infinite
* inflict
* influence
* inform
* infringe
* ingenious
* ingenuous
* ingredient
* inhabit
* inhale
* inhibit
* initial
* injure
* injustice
* inland
* innate
* inner
* innocence
* innovation
* input
* inquiry
* inscribe
* insert
* insight
* insist
* inspire
* install
* instance
* institute
* instruct
* insulate
* insurance
* integer
* integrate
* intellect
* intelligent
* intend
* intense
* intensify
* interact
* interfere
* interior
* internal
* interpret
* interrupt
* interval
* intervene
* interview
* intrigue
* introduce
* intrude
* invaluable
* invasion
* invent
* invest
* investigate
* invitation
* invoice
* involve
This is just a small sample of words starting with "in". The prefix "in" is very versatile and can be used to create a wide range of words with different meanings.