Final answer:
The 11-letter word meaning without a beard or mustache is 'beardless.' It signifies a lack of facial hair and can also imply youthfulness or inexperience.
Step-by-step explanation:
The 11-letter word meaning without a beard or mustache is ‘beardless’. When someone is described as beardless, it means they have no facial hair at all. This term can be used in various contexts, whether describing a person's appearance in a literal sense or when used figuratively to denote youthfulness or lack of maturity, since a beard is often associated with age and wisdom.