ail

Short definition from Wiktionary

Verb

1. 1
   To cause to suffer; to trouble, afflict. (Now chiefly in interrogative or indefinite constructions.)
2. 2
   To be ill; to suffer; to be troubled.

Noun

1. 1
   An ailment; trouble; illness.
2. 2
   The awn of barley or other types of corn.

Adjective

1. 1
   Painful; troublesome.