sickly in WordNet English dictionary

1. somewhat ill or prone to illness
   "my poor ailing grandmother"; "feeling a bit indisposed today"; "you look a little peaked"; "feeling poorly"; "a sickly child"; "is unwell and can't come to work"
   ailing  indisposed  peaked  poorly  sickly  unwell  under the weather  seedy 
   
2. unhealthy looking
   sallow  sickly