How do you classify a character's part size?

We use the following labels to classify characters' part sizes:

Lead Role: This character appears in most scenes in the show. The character is central to the story and the play/musical could not exist without him/her. Protagonist.

Supporting Role: A speaking character who appears in more than one scene. Important to the storyline, but recognizably not a lead character.

Featured Role: The actor has (approximately) one scene with one or more lines, could be cut from the script without dramatically altering the story.

Ensemble: Roles with little to no speaking or solo singing lines, and/or those who perform vocally in a group.