A character's Aspect refers to the physical body possessed by a character. It is found under a character's physical description in their profile. A character's aspect (their physical description) will change every time they die and return to life.
There are many aspects and each one is different. When a character respawns, a new aspect is chosen at random. Characters can choose a gender preference for this by editing their profile.
After a character transcends, ascends to Angelhood or descends to Demonkind they receive different aspects to reflect their class choice and can no longer gain a mortal aspect. This aspect change does not occur until they respawn and shed their current mortal aspect.
There is a distinct difference between an aspect and a character's personal description. The personal description is provided by the player, and does not describe what the character looks like.
The character's physical description is generated by the game itself. The description is a combination of the character's aspect as well as several equipped items (such as clothing) and skills that modify the character (like Blood Claws). For example, the description of a Pariah with Blood Claws will indicate that he possesses a set of sharp claws, while a Revenant with Shadow Armor will be described as wearing a suit of ghostly armor.
Further, characters in alternate forms (such as Divine Champions with Cloak of Steel activated) will also include this information.