Citations:unlike

Usage as a verb relating to Facebook:
 * 2009, Ben Zimmer, “On Language: The Age of Undoing”, in The New York Times Magazine, 2009 September 20, page MM8:
 * Facebook, for instance, allows you to register approval for a posted message in a very concrete way, by clicking a thumbs-up like button. Toggling off the button results in unliking your previously liked item. Note that this is different from disliking something, since unliking simply returns you to a neutral state.
 * 2010 June 25, "TheKorn" (username), "Re: Pinball: RGP and/or Facebook", in, Usenet:
 * My comment was more of a backhanded slap at Stern Pinball's Facebook "presence", specifically the garbage "cheap heat" posts.   It's so inane (and now, so constant) that I wound up "unliking" stern pinball entirely.