As nouns the difference between infant and hospitalism
is that
infant is a very young human being, from birth to somewhere between six months and two years of age, needing almost constant care and/or attention while
hospitalism is (psychology) wasting away of infants in long-term institutional care, caused by lack of contact with caregivers.
As a verb infant
is (obsolete) to bear or bring forth (a child); to produce, in general.