addle

addle \AD-'l\, verb:

1. to make or become muddled or confused
2. to make or become rotten or putrid

As TV audiences saw, it was enough to addle Fellow Oscar Winner Jon Voight's brain for the rest of the night.
-- Frank Rich, Pros at Play, Time, May 6, 1975

United Nations troops waited to take up their posts as guards to ensure that no liquor, women or bribe money was smuggled in to addle the judgment of the Deputies.
-- Empty Campus, Time, July 13, 1957

You'd think you'd have to be seriously dumb to be fooled in this way but there's undeniably something about residential property, whether an investment or simply a family home, that can addle the brains of otherwise quite sensible people.
-- Liz Dolan, Money surgery: keep property out of pensions, Daily Telegraph, May 17, 2001

by 1712, from addle (n.) "urine, liquid filth," from Old English adela "mud, mire, liquid manure" (cognate with Old Swedish adel "urine," Middle Low German adel, Dutch aal "puddle"). Used in noun phrase addle egg (c.1250) "egg that does not hatch, rotten egg," literally "urine egg," a loan translation of Latin ovum urinum, which is itself an erroneous loan translation of Greek ourion oon "putrid egg," literally "wind egg," from ourios "of the wind" (confused by Roman writers with ourios "of urine," from ouron "urine"). Because of this usage, the noun in English was taken as an adjective from c. 1600, meaning "putrid," and thence given a figurative extension to "empty, vain, idle," also "confused, muddled, unsound" (1706). The verb followed.