Source : Webster's Revised Unabridged Dictionary (1913)

Ache \Ache\, n. [OE. ache, AS. [ae]ce, ece, fr. acan to ache.
   See {Ache}, v. i.]
   Continued pain, as distinguished from sudden twinges, or
   spasmodic pain. ``Such an ache in my bones.'' --Shak.

   Note: Often used in composition, as, a headache, an earache,
         a toothache.

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.

Ach \Ach\, Ache \Ache\, n. [F. ache, L. apium parsley.]
   A name given to several species of plants; as, smallage, wild
   celery, parsley. [Obs.] --Holland.

Source : WordNet®

ache
     n : a dull persistent (usually moderately intense) pain [syn: {aching}]

ache
     v 1: feel physical pain; "Were you hurting after the accident?"
          [syn: {hurt}, {suffer}]
     2: have a desire for something or someone who is not present;
        "She ached for a cigarette"; "I am pining for my lover"
        [syn: {yearn}, {yen}, {pine}, {languish}]
     3: be the source of pain [syn: {smart}, {hurt}]