Both Uses

principal
in
A Walk to Remember
(Auto-generated)

The next morning I went to the principal's office and added my name to the list of candidates.†
Chpt 2 *

principal = most important; or person that is most important
The principal knew she was reading to them or doing crafts or just sitting around playing games with them.†
Chpt 2

Definitions:

(1) (principal)
most important; or person who is most important
The exact meaning of principal can depend upon its context. For example:
- "the principal idea" or "the principal performer" -- the most important
- "the principal of the school" -- the person in charge
- "a principal of a company" -- an owner or person with controlling authority
- "the principal in a transaction" (as contrasted to the agent) -- the person on whose behalf an agent acts
(2) (meaning too rare to warrant focus)
See a comprehensive dictionary for specialized senses in finance, architecture, law, chemistry, and music.