What is the "deferential abuse-of-discretion" standard in determining a reasonable sentence?

a "deferential abuse-of-discretion standard." United States v. Cavera, 550 F.3d 180, 189 (2d Cir. 2008) (en banc) (quoting Gall v. United States, 552 U.S. 38, 41 (2007)). A sentence is procedurally reasonable so long as the district court did not commit a "significant procedural error, such as failing to calculate (or improperly calculating) the Guidelines range, treating the Guidelines as mandatory, failing to consider the [18 U.S.C.] 3553(a) factors, selecting a sentence based on clearly erroneous facts, or failing to adequately explain the chosen sentence -- including an explanation for any deviation from the Guidelines range." Gall, 552 U.S. at 51.