- incapable
- in the balance
- in decline
- infectious
- in the doldrums
- in doubt
- in high dudgeon
- in any event, at all events
- in evidence
- in fact
- in favour of
- in fits and starts, by fits and starts
- in force
- in fun
- ice-cold
- idealist
- ideology
- idol
- if
- ignominious
- ilk
- ill-advised
- illusory
- illustrious
- imbalance
- immaculate
- impale
- impinge
- implacable
- implication
- impolitic
- impose oneself
- impossible
- impostor
- impromptu
- improvise
- impurity
- inadequate
- incivility
- inappreciable
- incline
- incognito
- incensed
- inception
- incidence
- incomparably
- indefinable
- independent
- indicated
- indication
- indiscreet
- indistinguishable
- industrious
- inexpensive
- inexplicable
- infantry
- infiltrate
- inflate
- informed
- inherent
- inhibit
- injudicious
- insistent
- instalment
- instant
- instigator
- instinct
- instruction
- instructor
- instrumental
- insubordinate
- intense
- intensive
- intrigue
- invalid
- inventory
- irrecoverable
- isolated
- in a jiffy
- in limbo
- in our midst
- in the mood
- in motion
- in need
- in operation
- in good part
- in practice
- in preference to
- in public
- in question
- in scale
- in a tick in a second
- in transit
- in turn one by one
- issued
- impercipient
- iron bar
- immovability
- individual soul
- inner house