ache

Short definition from Wiktionary

Verb

1. 1
   To suffer pain; to be the source of, or be in, pain, especially continued dull pain; to be distressed.
2. 2
   To cause someone or something to suffer pain.

Noun

1. 1
   Continued dull pain, as distinguished from sudden twinges, or spasmodic pain.
2. 2
   Parsley.
3. 3
   Rare spelling of aitch.
4. 4
   Abbreviation of acetylcholinesterase.

Proper noun

1. 1
   A language spoken by the Yi people of South-Western China.