The Collaborative International Dictionary of English v.0.48:

Imp \Imp\ ([i^]mp), n. [OE. imp a graft, AS. impa; akin to Dan.
   ympe, Sw. ymp, prob. fr. LL. impotus, Gr. ? engrafted,
   innate, fr. ? to implant; ? in + ? to produce; akin to E. be.
   See 1st In-, Be.]
   1. A shoot; a scion; a bud; a slip; a graft. [Obs.]
      --Chaucer.
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   2. An offspring; progeny; child; scion. [Obs.]
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            The tender imp was weaned.            --Fairfax.
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   3. A young or inferior devil; a little, malignant spirit; a
      puny demon; a contemptible evil worker.
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            To mingle in the clamorous fray
            Of squabbling imps.                   --Beattie.
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   4. Something added to, or united with, another, to lengthen
      it out or repair it, -- as, an addition to a beehive; a
      feather inserted in a broken wing of a bird; a length of
      twisted hair in a fishing line. [Obs. or Prov. Eng.]
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The Collaborative International Dictionary of English v.0.48:

Imp \Imp\, v. t. [imp. & p. p. Imped; p. pr. & vb. n.
   Imping.] [AS. impian to imp, ingraft, plant; akin to Dan.
   ympe, Sw. ympa, OHG. impf[=o]n, impit[=o]n, G. impfen. See
   Imp, n.]
   1. To graft; to insert as a scion. [Obs.] --Rom. of R.
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   2. (Falconry) To graft with new feathers, as a wing; to
      splice a broken feather. Hence, [Fig.]: To repair; to
      extend; to increase; to strengthen; to equip. [Archaic]
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            Imp out our drooping country's broken wing. --Shak.
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            Who lazily imp their wings with other men's plumes.
                                                  --Fuller.
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            Here no frail Muse shall imp her crippled wing.
                                                  --Holmes.
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            Help, ye tart satirists, to imp my rage
            With all the scorpions that should whip this age.
                                                  --Cleveland.
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WordNet (r) 3.0 (2006):

imp
    n 1: (folklore) fairies that are somewhat mischievous [syn:
         elf, hob, gremlin, pixie, pixy, brownie, imp]
    2: one who is playfully mischievous [syn: imp, scamp,
       monkey, rascal, rapscallion, scalawag, scallywag]

The Free On-line Dictionary of Computing (19 January 2023):

IMP

   1.  IMProved Mercury autocode.

   2.  An extensible dialect of ALGOL 60, for CDC
   1604.

   ["Experience with an Extensible Language", Edgar T. Irons,
   CACM 13(1):31-39, Jan 1970].

   3.  Interpretive Menu Processor.

   4.  IMPlementation language.

   5.  Interface Message Processor.

   (1996-04-07)