Source : Webster's Revised Unabridged Dictionary (1913)

Ache \Ache\, v. i. [imp. & p. p. {Ached}; p. pr. & vb. n.
   {Aching}.] [OE. aken, AS. acan, both strong verbs, AS. acan,
   imp. [=o]c, p. p. acen, to ache; perh. orig. to drive, and
   akin to agent.]
   To suffer pain; to have, or be in, pain, or in continued
   pain; to be distressed. ``My old bones ache.'' --Shak.

         The sins that in your conscience ache.   --Keble.

Aching \Ach"ing\, a.
   That aches; continuously painful. See {Ache}. --
   {Ach"ing*ly}, adv.

         The aching heart, the aching head.       --Longfellow.

Source : WordNet®

aching
     adj : causing a dull and steady pain; "my aching head"; "her old
           achy joints" [syn: {achy}]
     n : a dull persistent (usually moderately intense) pain [syn: {ache}]