benefactor a person who helps people or institutions
car factory a factory where automobiles are manufactured
scale factor a number used as a multiplier in scaling
prime factor the prime factors of a quantity are all of the prime quantities that will exactly divide the given quantity
perfecter a skilled worker who perfects something
growth factor a protein that is involved in cell differentiation and growth
Pyrrhic victory a victory that is won by incurring terrible losses
Rh factor a blood group antigen possessed by Rh-positive people
prefecture the district administered by a prefect
fudge factor a quantity that is added or subtracted in order to increase the accuracy of a scientific measure
breeder reactor a nuclear reactor that produces more fissile material than it burns
calefactory serving to heat
Hageman factor coagulation factor whose deficiency results in prolongation of clotting time of venous blood
cofactor a substance (as a coenzyme) that must join with another to produce a given result
nuclear reactor (physics) any of several kinds of apparatus that maintain and control a nuclear reaction for the production of energy or artificial elements
multiplier factor the number by which a multiplicand is multiplied
malefactor someone who has committed a crime
perfectly in a perfect or faultless way
refectory a communal dining-hall, usually in a monastery
provocateur a secret agent who incites persons to commit illegal acts