The Collaborative International Dictionary of English v.0.48:

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.
   [1913 Webster]

         The sins that in your conscience ache.   --Keble.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Aching \Ach"ing\, a.
   That aches; continuously painful. See Ache. --
   Ach"ing*ly, adv.
   [1913 Webster]

         The aching heart, the aching head.       --Longfellow.
   [1913 Webster]

WordNet (r) 3.0 (2006):

aching
    adj 1: causing a dull and steady pain; "my aching head"; "her
           old achy joints" [syn: aching, achy]
    n 1: a dull persistent (usually moderately intense) pain [syn:
         ache, aching]