Wordnet 3.0
ADJECTIVE (1)
1. 
 causing a dull and steady pain; 
- Example: "my aching head"- Example: "her old achy joints"[syn: aching, achy]
WordNet (r) 3.0 (2006):
achy
    adj 1: causing a dull and steady pain; "my aching head"; "her
           old achy joints" [syn: aching, achy]