The naming of Ubuntu 11.10 (Oneiric Ocelot) was announced on 7 March 2011 by Mark Shuttleworth. He explained that Oneiric means "dreamy". Ubuntu 11.10 was released on schedule on 13 October 2011 and is Canonical's 15th release of Ubuntu.
In April 2011, Shuttleworth announced that Ubuntu 11.10 would not include the classic GNOME desktop as a fall back to Unity, unlike Ubuntu 11.04 Natty Narwhal. Instead, 11.10 included a 2D version of Unity as a fallback for computers that lacked the hardware resources for the Compiz-based 3D version. However, the classic GNOME desktop remained available in Ubuntu 11.10 through a package in the Ubuntu repositories. Shuttleworth also confirmed that Unity in Ubuntu 11.10 would run as a shell for GNOME 3 on top of GNOME 3 libraries, unlike in Ubuntu 11.04 where it ran as a shell for GNOME 2. Moreover, users were able to install the entire GNOME 3 stack along with GNOME Shell directly from the Ubuntu repositories; to be presented with a "GNOME 3 desktop" choice at login. During the development cycle there were many changes to Unity, including the placement of the Ubuntu button on the Launcher instead of on the Panel, the autohiding of the window controls (and the global menu) of maximized windows, the introduction of more transparency into the Dash (and the Panel when the Dash was opened) and the introduction of window controls for the Dash.
In May 2011, it was announced that Pitivi would be no longer part of the Ubuntu ISO, starting with Ubuntu 11.10 Oneiric Ocelot. The reasons given for removing it included poor user reception, lack of fit with the default user-case for Ubuntu, lack of polish and the application's lack of development maturity. PiTiVi will not be replaced on the ISO with another video editor. Other changes include removing Computer Janitor, as it caused broken systems for users, and the removal of the Synaptic package manager, which can optionally be installed via the Ubuntu Software Center. Déjà Dup has been added as Ubuntu's backup program. Mozilla Thunderbird has replaced the GNOME Evolution email client. All removed applications will remain available to users for installation from the Ubuntu Software Center and repositories.
Support for Ubuntu Oneiric Ocelot was officially ended on 9 May 2013.