Merriam-Webster Collegiate Dictionary - unlike

 I. adjective  Date: 13th century not like: as  a. marked by lack of resemblance ; different the two books are quite ~  b. marked by inequality ; unequal contributed ~ amounts  • ~ness noun  II. preposition  Date: circa 1592 not like: as  a. different from a landscape ~ any other  b. not characteristic of it was ~ him to be late  c. in a different manner from spoke clearly, ~ the others  III. conjunction  Date: 1949 in a manner that is different than ; not as Usage:  The use of ~ as a conjunction is less common than conjunctive use of like and, while criticized, is not as frequently cited as an error. The conjuctive ~ almost always introduces a prepositional phrase ~ 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 ~ is well established in both American and British English.