The Collaborative International Dictionary of English v.0.48:

Mizzle \Miz"zle\, v. i. [imp. & p. p. Mizzled; p. pr. & vb. n.
   Mizzling.] [See Misle, and cf. Mistle.]
   1. To rain in very fine drops; to drizzle. --Spenser.
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   2. To take one's self off; to go. [Slang]
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            As long as George the Fourth could reign, he
            reigned,
            And then he mizzled.                  --Epigram,
                                                  quoted by
                                                  Wright.
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