Real Dictionary

ache
An ache is a steady, fairly strong pain in a part of your body.
verb: If you ache for something or your heart aches, you want something very much, and feel very unhappy because you cannot have it.
verb: If you ache or a part of your body aches, you feel a steady, fairly strong pain.

ache in American English
to have or give dull, steady pain
intransitive verb: to have or suffer a continuous, dull pain
noun: a continuous, dull pain (in contrast to a sharp, sudden, or sporadic pain)

ache in British English
to feel, suffer, or be the source of a continuous dull pain
noun: a continuous dull pain