fac-, facil-, fact-, feas-, -feat, -fect, -feit, -facient, -faction, -fic-, -fy, -ficate, -fication

(Latin: to make, to do, to build, to cause, to produce; forming, shaping)

indemnifier
indemnify
ineffective
ineffectiveness
ineffectual
ineffectually
ineffectualness
inefficacity
inefficiency
inefficient
inefficiently
infect
infection
infectious
infectiously