In geometry, an oblique object is one that is distorted so that is seems to 'lean over' at an angle, as opposed to being exactly upright. One that is not oblique and is upright is called a 'right' object. A way to remember which is which is that 'right' objects are 'upRIGHT'. For example see the right cylinder and oblique cylinder below.

The shape is distorted by sliding the top sideways so it is not directly above the bottom. It is not formed by simply tipping it on one corner: