The Collaborative International Dictionary of English v.0.48:

Addle \Ad"dle\, v. t. & i. [OE. adlen, adilen, to gain, acquire;
   prob. fr. Icel. ["o][eth]lask to acquire property, akin to
   o[eth]al property. Cf. Allodial.]
   1. To earn by labor. [Prov. Eng.] --Forby.
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   2. To thrive or grow; to ripen. [Prov. Eng.]
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            Kill ivy, else tree will addle no more. --Tusser.
      [1913 Webster] Addle-head
      Addle-brain

The Collaborative International Dictionary of English v.0.48:

Addle \Ad"dle\, n. [OE. adel, AS. adela, mud.]
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   1. Liquid filth; mire. [Obs.]
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   2. Lees; dregs. [Prov. Eng.] --Wright.
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The Collaborative International Dictionary of English v.0.48:

Addle \Ad"dle\, a.
   Having lost the power of development, and become rotten, as
   eggs; putrid. Hence: Unfruitful or confused, as brains;
   muddled. --Dryden.
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The Collaborative International Dictionary of English v.0.48:

Addle \Ad"dle\, v. t. & i. [imp. & p. p. Addled; p. pr. & vb.
   n. Addling.]
   To make addle; to grow addle; to muddle; as, he addled his
   brain. "Their eggs were addled." --Cowper.
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WordNet (r) 3.0 (2006):

addle
    v 1: mix up or confuse; "He muddled the issues" [syn: addle,
         muddle, puddle]
    2: become rotten; "addled eggs"