The Collaborative International Dictionary of English v.0.48:

Lady \La"dy\ (l[=a]"d[y^]), n.; pl. Ladies (l[=a]"d[i^]z).
   [OE. ladi, l[ae]fdi, AS. hl[=ae]fdige, hl[=ae]fdie; AS.
   hl[=a]f loaf + a root of uncertain origin, possibly akin to
   E. dairy. See Loaf, and cf. Lord.]
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   1. A woman who looks after the domestic affairs of a family;
      a mistress; the female head of a household.
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            Agar, the handmaiden of Sara, whence comest thou,
            and whither goest thou? The which answered, Fro the
            face of Sara my lady.                 --Wyclif (Gen.
                                                  xvi. 8.).
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   2. A woman having proprietary rights or authority; mistress;
      -- a feminine correlative of lord. "Lord or lady of high
      degree." --Lowell.
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            Of all these bounds, even from this line to this, .
            . .
            We make thee lady.                    --Shak.
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   3. A woman to whom the particular homage of a knight was
      paid; a woman to whom one is devoted or bound; a
      sweetheart.
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            The soldier here his wasted store supplies,
            And takes new valor from his lady's eyes. --Waller.
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   4. A woman of social distinction or position. In England, a
      title prefixed to the name of any woman whose husband is
      not of lower rank than a baron, or whose father was a
      nobleman not lower than an earl. The wife of a baronet or
      knight has the title of Lady by courtesy, but not by
      right.
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   5. A woman of refined or gentle manners; a well-bred woman;
      -- the feminine correlative of gentleman.
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   6. A wife; -- not now in approved usage. --Goldsmith.
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   7. Hence: Any woman; as, a lounge for ladies; a cleaning
      lady; also used in combination; as, saleslady.
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   8. (Zool.) The triturating apparatus in the stomach of a
      lobster; -- so called from a fancied resemblance to a
      seated female figure. It consists of calcareous plates.
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   Ladies' man, a man who affects the society of ladies.

   Lady altar, an altar in a lady chapel. --Shipley.

   Lady chapel, a chapel dedicated to the Virgin Mary.

   Lady court, the court of a lady of the manor.

   Lady crab (Zool.), a handsomely spotted swimming crab
      (Platyonichus ocellatus) very common on the sandy shores
      of the Atlantic coast of the United States.

   Lady fern. (Bot.) See Female fern, under Female, and
      Illust. of Fern.

   Lady in waiting, a lady of the queen's household, appointed
      to wait upon or attend the queen.

   Lady Mass, a Mass said in honor of the Virgin Mary.
      --Shipley.

   Lady of the manor, a lady having jurisdiction of a manor;
      also, the wife of a manor lord.

   Lady's maid, a maidservant who dresses and waits upon a
      lady. --Thackeray.

   Our Lady, the Virgin Mary.
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