1-Merriam-Webster Online	http://www.m-w.com/
2-Unified Medical Dictionary :The Unified Medical Dictionary ( UMD) is an English/Arabic Medical Dictionary	http://www.emro.who.int/umd/
3-MEDLINEplus : Medical Dictionary	http://www.nlm.gov/medlineplus/
4- Medical Dictionary	http://medical-dictionary.com/