From WordNet (r) 2.0 [wn]:
1: not smiling
From Moby Thesaurus II by Grady Ward, 1.0 [moby-thes]:
41 Moby Thesaurus words for "unsmiling": cheerless, decorous, demure, discontented, earnest, formal, frowning, grave, grim, grim-faced, grim-visaged, humorless, in bad humor, infestive, joyless, long-faced, mirthless, miserable, out of humor, out of sorts, pleasureless, sedate, serious, sober, sober-minded, sobersided, solemn, somber, sorry, sorryish, staid, stone-faced, straight-faced, thoughtful, uncheerful, uncheery, unhappy, unjoyful, unmirthful, weighty, wretched
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