unlike

Concise Oxford English Dictionary © 2008 Oxford University Press:
unlike/ʌnˈlʌɪk/

▶preposition different from; not like.

■ in contrast to.

■ uncharacteristic of.

▶adjective dissimilar or different from each other.

■ (unlike to/from) archaic different from.

– derivatives
unlikeness noun.

– origin ME: perh. orig. an alt. of ON úlíkr; cf. OE ungelīc.

usage: The use of unlike as a conjunction, as in she was behaving unlike she'd ever behaved before, is not considered standard English. It can be avoided by using as with a negative instead: she was behaving as she'd never behaved before.