An actor no one has ever heard of who is trying to get into the movie business is an example of an unknown.
In the equation "x+2 = 4," x is an example of an unknown.
A problem unknown in earlier times.
Received flowers from an unknown admirer.
An unknown artist.
Investigating the unknown.
This case has many unknowns.
Cast an unknown in the starring role.
The tomb of the unknowns.
- Not in the knowledge, understanding, or acquaintance of someone; unfamiliar (to).
- Not discovered, identified, determined, explored, etc.
A brand new taste that you have never tasted before is an example of something that you would describe as an unknown taste.