1711, "that concerns, important" (archaic), present-participle adjective from interest (v.). Meaning "engaging the attention, so as to excite interest" is from 1751. Related: Interestingly. Euphemistic phrase interesting condition, etc., "pregnant" is from 1748.
interdict
interdiction
interdisciplinary
interest
interested
interesting
interface
interfacial
interfaith
interfere
interference