perpetuity
    n 1: the property of being perpetual (seemingly ceaseless) [syn:
         perpetuity, sempiternity]

Perpetuity \Per`pe*tu"i*ty\, n. [L. perpetuitas: cf. F.
   perp['e]tuit['e].]
   1. The quality or state of being perpetual; as, the
      perpetuity of laws. --Bacon.
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            A path to perpetuity of fame.         --Byron.
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            The perpetuity of a single emotion is insanity. --I.
                                                  Taylor.
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   2. Something that is perpetual. --South.
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   3. Endless time. "And yet we should, for perpetuity, go hence
      in debt." --Shak.
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   4. (Annuities)
      (a) The number of years in which the simple interest of
          any sum becomes equal to the principal.
      (b) The number of years' purchase to be given for an
          annuity to continue forever.
      (c) A perpetual annuity.
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   5. (Law)
      (a) Duration without limitations as to time.
      (b) The quality or condition of an estate by which it
          becomes inalienable, either perpetually or for a very
          long period; also, the estate itself so modified or
          perpetuated.
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PERPETUITY, estates. Any limitation tending to take the subject of it out of 
commerce for a longer period than a life or lives in being, and twenty-one 
years beyond; and in case of a posthumous child, a few months more, allowing 
for the term of gestation; Randall on Perpetuities, 48; or it is such a 
limitation of property as renders it unalienable beyond the period allowed 
by law. Gilbert on Uses, by Sugden, 260, note. 
     2. Mr. Justice Powell, in Scattergood v. Edge, 12 Mod. 278, 
distinguished perpetuities into two sorts, absolute and qualified; meaning 
thereby, as it is apprehended, a distinction between a plain, direct and 
palpable perpetuity, and the case where an estate is limited on a 
contingency, which might happen within a reasonable compass of time, but 
where the estate nevertheless, from the nature of the limitation, might be 
kept out of commerce longer than was thought agreeable to the policy of the 
common law. But this distinction would not now lead to a better 
understanding or explanation of the subject; for whether an estate be so 
limited that it cannot take effect, until a period too much protracted, or 
whether on a contingency which may happen within a moderate compass of time, 
it equally falls within the line of perpetuity and the limitation is 
therefore void; for it is not sufficient that an estate may vest within the 
time allowed, but the rule requires that it must. Randall on Perp. 49. Vide 
Cruise, Dig. tit. 32, c. 23; 1 Supp. to Ves. Jr. 406; 2 Ves. Jr. 357; 3 
Saund. 388 h. note; Com. Dig. Chancery, 4 G 1; 3 Chan. Cas. 1; 2 Bouv. Inst. 
n. 1890.