The Collaborative International Dictionary of English v.0.48:

Dapper \Dap"per\, a. [OE. daper; prob. fr. D. dapper brave,
   valiant; akin to G. tapfer brave, OHG. taphar heavy, weighty,
   OSlav. dobr[u^] good, Russ. dobrui. Cf. Deft.]
   Little and active; spruce; trim; smart; neat in dress or
   appearance; lively.
   [1913 Webster]

         He wondered how so many provinces could be held in
         subjection by such a dapper little man.  --Milton.
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         The dapper ditties that I wont devise.   --Spenser.
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         Sharp-nosed, dapper steam yachts.        --Julian
                                                  Hawthorne.
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WordNet (r) 3.0 (2006):

dapper
    adj 1: marked by up-to-dateness in dress and manners; "a dapper
           young man"; "a jaunty red hat" [syn: dapper, dashing,
           jaunty, natty, raffish, rakish, spiffy,
           snappy, spruce]