The Collaborative International Dictionary of English v.0.48:

Sad \Sad\ (s[a^]d), a. [Compar. Sadder (s[a^]d"d[~e]r);
   superl. Saddest.] [OE. sad sated, tired, satisfied, firm,
   steadfast, AS. saed satisfied, sated; akin to D. zat, OS.
   sad, G. satt, OHG. sat, Icel. sa[eth]r, saddr, Goth.
   sa[thorn]s, Lith. sotus, L. sat, satis, enough, satur sated,
   Gr. 'a`menai to satiate, 'a`dnh enough. Cf. Assets, Sate,
   Satiate, Satisfy, Satire.]
   1. Sated; satisfied; weary; tired. [Obs.]
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            Yet of that art they can not waxen sad,
            For unto them it is a bitter sweet.   --Chaucer.
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   2. Heavy; weighty; ponderous; close; hard. [Obs., except in a
      few phrases; as, sad bread.]
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            His hand, more sad than lump of lead. --Spenser.
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            Chalky lands are naturally cold and sad. --Mortimer.
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   3. Dull; grave; dark; somber; -- said of colors. "Sad-colored
      clothes." --Walton.
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            Woad, or wade, is used by the dyers to lay the
            foundation of all sad colors.         --Mortimer.
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   4. Serious; grave; sober; steadfast; not light or frivolous.
      [Obs.] "Ripe and sad courage." --Chaucer.
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            Lady Catharine, a sad and religious woman. --Bacon.
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            Which treaty was wisely handled by sad and discrete
            counsel of both parties.              --Ld. Berners.
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   5. Affected with grief or unhappiness; cast down with
      affliction; downcast; gloomy; mournful.
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            First were we sad, fearing you would not come;
            Now sadder, that you come so unprovided. --Shak.
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            The angelic guards ascended, mute and sad. --Milton.
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   6. Afflictive; calamitous; causing sorrow; as, a sad
      accident; a sad misfortune.
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   7. Hence, bad; naughty; troublesome; wicked. [Colloq.] "Sad
      tipsy fellows, both of them." --I. Taylor.
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   Note: Sad is sometimes used in the formation of
         self-explaining compounds; as, sad-colored, sad-eyed,
         sad-hearted, sad-looking, and the like.
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   Sad bread, heavy bread. [Scot. & Local, U.S.] --Bartlett.
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   Syn: Sorrowful; mournful; gloomy; dejected; depressed;
        cheerless; downcast; sedate; serious; grave; grievous;
        afflictive; calamitous.
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The Collaborative International Dictionary of English v.0.48:

Sadder \Sad"der\, n.
   Same as Sadda.
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