- indivisible atom
- in decline
- in the doldrums
- in doubt
- in any event, at all events
- in evidence
- in fact
- in favour of
- in fits and starts, by fits and starts
- in fun
- ice-cold
- idol
- ilk
- ill-advised
- illusory
- illustrious
- imbalance
- immaculate
- impale
- implication
- impolitic
- impose oneself
- impossible
- impromptu
- improvise
- impurity
- inappreciable
- incognito
- inception
- incidence
- incomparably
- indefinable
- independent
- indicated
- indication
- indistinguishable
- industrious
- inexplicable
- inflate
- inherent
- instant
- instigator
- instinct
- instruction
- instructor
- instrumental
- insubordinate
- intensive
- intrigue
- invalid
- inventory
- irrecoverable
- in a jiffy
- in the mood
- in motion
- in need
- in operation
- in good part
- in preference to
- in public
- in question
- in scale
- in a tick in a second
- issued
- impercipient
- iron bar
- immovability
- individual soul
- inner house
- inward decay
- intrinsic worth
- incurvate
- impressionistic
- inspector of taxes
- interspace
- inert gas
- insole
- inaptitude
- ingenue
- infamies
- ideate
- intraday
- illegal operation
- intestinal disorder
- internationalist
- in round figures
- in small way
- inhospitableness
- inner eye
- immoral path
- inverted commas
- isopod
- injured person
- iupac
- inner soul
- in a measure
- injury time
- israelite
- instancy
- intestine