in; into; towards; within; on: infiltrate, immigrate
2.
having an intensive or causative function: inflame, imperil
Word Origin
from in (prep, adv)
Word Origin and History for im-
variant of in- before -b-, -m-, -p-, in the sense of "not, opposite of" (immobile, impersonal) as well as "in, into" (implant, impoverish). See in-. In some English words it alternates with em- (1).