Below are a range of online medical dictionaries sourced from reliable Australian organisations.

Better Health
Reliable health information from the Victorian Government

State Library
Medical dictionaries from the State Library of New South Wales

Medline Plus

Health Insite
www.healthinsite.gov.au

Cochrane Library
http://www3.interscience.wiley.com/cgi-bin/mrwhome/106568753/HOME/

Patient Information Leaflets
http://www.health.nsw.gov.au/ 

Heart disease publications.
www.heartfoundation.com.au/index.cfm?page=11

Diabetes information.
http://www.diabetesaustralia.com.au/fact_sheets/index.html

Juvenile diabetes information.
http://www.jdrf.org.au/publications/brochures.htm

Stroke Foundation
http://www.strokefoundation.com.au/pages/Default.aspx?PageID=15&id=1

Prostate Cancer
http://www.prostate.org.au/BAM-DL.htm
http://www.prostatehealth.org.au/v3/index.htm

Brilliant stuff for the public on cancer...
http://www.cancercouncil.com.au/canceranswers/

Solid info on Breast cancer
http://www.breasthealth.com.au/whatisbreastcancer/index.html

Mental Health depression and suicide
http://www.beyondblue.org.au/index.aspx?link_id=7.246
http://www.sane.org/index.php?option=displaypage&Itemid=297&op=page

Leukaemia
http://www.leukaemia.com.au/leukaemia-foundation/web/index.asp?m1=13&pg=62#underIf

The good old NHL Non-Hodgkin's Lymphoma
http://www.cancercouncil.com.au/editorial.asp?pageid=71

One stop shop for Asthma
http://www.nationalasthma.org.au/publications.html

A summary for those with a bun in the oven:
http://www.pregnancy.com.au/topics_of_interest.htm

Teenage pregnancy
http://www.womhealth.org.au/studenfactsheets/teenagepregnancy.htm

Gay rights
http://www.glrl.org.au/publications/fact_sheets.htm

AIDS
http://www.afao.org.au/view_articles.asp?pxs=103&pxsc=127&pxsgc=137&pxa=ve&id=310
http://www.afao.org.au/view_articles.asp?pxs=103&pxsc=160&pxsgc=&pxa=ve&id=185

Thrush
http://www.stdservices.on.net/std/candidiasis/facts.htm

Royal Adelaide's STD units fact sheets
http://www.stdservices.on.net/publications/pamphlets.htm

The Flu and its vaccine
http://immunise.health.gov.au/public.htm

Poisons
http://www.rch.org.au/poisons/health-info.cfm?doc_id=3638

Tobacco/smoking facts
http://www.newint.org/issue369/facts.htm

Travel medicine fact sheets
http://www.tmvc.com.au/healthy.asp?UnqID=0.3655584&PageID=18

Health News
http://abc.net.au/health/