The Collaborative International Dictionary of English v.0.48:

Seemly \Seem"ly\ (s[=e]m"l[y^]), a. [Compar.Seemlier
   (s[=e]m"l[i^]*[~e]r); superl. Seeliest.] [Icel.
   s[ae]miligr, fr. s[ae]mr becoming, fit; akin to samr same, E.
   same; the sense being properly, the same or like, hence,
   fitting. See Seem, v. i.]
   Suited to the object, occasion, purpose, or character;
   suitable; fit; becoming; comely; decorous.
   [1913 Webster]

         He had a seemly nose.                    --Chaucer.
   [1913 Webster]

         I am a woman, lacking wit
         To make a seemly answer to such persons. --Shak.
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         Suspense of judgment and exercise of charity were safer
         and seemlier for Christian men than the hot pursuit of
         these controversies.                     --Hooker.
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   Syn: Becoming; fit; suitable; proper; appropriate; congruous;
        meet; decent; decorous.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Seemly \Seem"ly\ (s[=e]m"l[y^]), adv. [Compar. Seemlier;
   superl. Seemliest.]
   In a decent or suitable manner; becomingly.
   [1913 Webster]

         Suddenly a men before him stood,
         Not rustic as before, but seemlier clad,
         As one in city or court or place bred.   --Milton.
   [1913 Webster]

WordNet (r) 3.0 (2006):

seemly
    adj 1: according with custom or propriety; "her becoming
           modesty"; "comely behavior"; "it is not comme il faut for
           a gentleman to be constantly asking for money"; "a decent
           burial"; "seemly behavior" [syn: becoming, comely,
           comme il faut, decent, decorous, seemly]

Moby Thesaurus II by Grady Ward, 1.0:

94 Moby Thesaurus words for "seemly":
   accepted, according to Hoyle, acknowledged, admitted, advantageous,
   advisable, apposite, appropriate, approved, apropos, apt, becoming,
   befitting, being done, characteristic, civil, comely,
   comme il faut, compatible, condign, conformable, conforming,
   congenial, congruous, consistent, consonant, convenient,
   conventional, correct, customary, de rigueur, decent, decorous,
   delicate, desirable, dignified, diplomatic, discreet, due, elegant,
   expedient, favorable, feasible, felicitous, fit, fitten, fitting,
   formal, fructuous, genteel, gentlemanly, good, happy, inspired,
   just, kosher, ladylike, likely, meet, modest, nice, normal,
   normative, opportune, orthodox, pleasing, politic, profitable,
   proper, prudent, reasonable, received, recognized, recommendable,
   right, right and proper, righteous, rightful, seasonable, sensible,
   sortable, suitable, suited, timely, to be desired, traditional,
   urbane, useful, well-chosen, well-expressed, well-put, well-timed,
   wise, worthwhile