Ubuntu Release Naming Scheme

The official name of an Ubuntu release is "Ubuntu X.YY" with X representing the year (minus 2000) and YY representing the month of eventual release within in that year. Ubuntu's first release, made in 2004 October (10th month) was Ubuntu 4.10. Since the actual release date is not known until it's ready and humans tend to prefer names rather than numbers, a set of code names are used by developers and testers during the build up to a release:

Adjective	Animal	Version	Description
Warty	Warthog	4.10	The first "hog"
Hoary	Hedgehog	5.04	Meaning "covered with hair", or "mature/old/wise"
Breezy	Badger	5.10	was going to be "Bendy Badger"...
Dapper	Drake	6.06	Polished, with 5 years of support!
Edgy	Eft	6.10	Fire up the crackpipes! (?!)
Feisty	Fawn	7.04	Courage and restlessness
Gutsy	Gibbon	7.10	Go Ape!
Hardy	Heron	8.04	Hardy Heron with 5 years of support! Most people wanted Happy/Hungry Hippo
Intrepid	Ibex	8.10	Released October 2008
Jaunty	Jackalope	9.04	Released April 2009
Karmic	Koala	9.10	Released October 2009
Lucid	Lynx	10.04

The development codename of a release takes the form "Adjective Animal". So for example: Warty Warthog (Ubuntu 4.10), Hoary Hedgehog (Ubuntu 5.04), Breezy Badger (Ubuntu 5.10), are the first three releases of Ubuntu. In general, people refer to the release using the adjective, like "warty" or "breezy".