— acting
— ephemeral
— episodic
— evanescent
— finite
— fly-by-night
— fugacious
— here today and gone tomorrow
— here today gone tomorrow
— impairment
— imperative
— imperfect
— imperial
— imperiled
— impermeable
— impersonal
— impersonate
— impertinence
— impertinent
— importance
— important
— importune
— impregnated
— imprint
— imprisonment
— improvement
— improvident
— improvised
— imprudent
— informant
— interim
— jury-rigged
— makeshift
— passing
— pro tem
— pro tempore
— shipboard
— short-lived
— temporal
— terminable
— transient
— transitory
— unstable
— working