I. -ˈlīk adjective
Date: 13th century
: not like: as
a. : marked by lack of resemblance : different
the two books are quite unlike
b. : marked by inequality : unequal
contributed unlike amounts
• un·like·ness noun
II. preposition
Date: circa 1592
: not like: as
a. : different from
a landscape unlike any other
b. : not characteristic of
it was unlike him to be late
c. : in a different manner from
spoke clearly, unlike the others
III. conjunction
Date: 1949
: in a manner that is different than : not as
Usage:
The use of unlike as a conjunction is less common than conjunctive use of like and, while criticized, is not as frequently cited as an error. The conjuctive unlike almost always introduces a prepositional phrase
unlike in other areas, the judiciary cannot justify its attempt…as a necessary evil — Alexandra M. Walsh, Stanford Law Review
In spite of criticism, this conjunctive use of unlike is well established in both American and British English.