Admittance means being allowed to enter a place or join a group. When you gain admittance to a museum, the staff permits you to go inside. When a student earns admittance to a prestigious high school, the school has accepted their application and said yes, you can come here.

The word carries a formal tone. You might say “my ticket got me into the concert,” but a sign at the theater reads “No admittance without a ticket.” Colleges send letters of admittance to students they've accepted. A hospital might restrict admittance to the emergency room to patients and their families only.

Admittance often implies that someone in authority has granted permission. You don't just wander into a courtroom during a trial: you need admittance from court officials. A backstage pass gives you admittance to areas where regular concertgoers can't go. The word suggests both the physical act of entering and the official permission that makes it possible.

Don't confuse admittance with admission, though they're related. Admission can mean the same thing, but it also means confessing something (“his admission of guilt”) or the price you pay to enter (“admission costs ten dollars”).