Source : Webster's Revised Unabridged Dictionary (1913)

Attenuate \At*ten"u*ate\, v. t. [imp. & p. p. {Attenuated}; p.
   pr. & vb. n. {Attenuating}.] [L. attenuatus, p. p. of
   attenuare; ad + tenuare to make thin, tenuis thin. See
   {Thin}.]
   1. To make thin or slender, as by mechanical or chemical
      action upon inanimate objects, or by the effects of
      starvation, disease, etc., upon living bodies.

   2. To make thin or less consistent; to render less viscid or
      dense; to rarefy. Specifically: To subtilize, as the
      humors of the body, or to break them into finer parts.

   3. To lessen the amount, force, or value of; to make less
      complex; to weaken.

            To undersell our rivals . . . has led the
            manufacturer to . . . attenuate his processes, in
            the allotment of tasks, to an extreme point. --I.
                                                  Taylor.

            We may reject and reject till we attenuate history
            into sapless meagerness.              --Sir F.
                                                  Palgrave.

Attenuate \At*ten"u*ate\, v. i.
   To become thin, slender, or fine; to grow less; to lessen.

         The attention attenuates as its sphere contracts.
                                                  --Coleridge.

Attenuate \At*ten"u*ate\, Attenuated \At*ten"u*a`ted\, a. [L.
   attenuatus, p. p.]
   1. Made thin or slender.

   2. Made thin or less viscid; rarefied. --Bacon.

Source : WordNet®

attenuate
     adj : reduced in strength; "the faded tones of an old recording"
           [syn: {attenuated}, {faded}, {weakened}]

attenuate
     v 1: weaken the consistency of (a chemical substance) [syn: {rarefy}]
     2: become weaker, in strength, value, or magnitude