sir

1. sir (noun) — sense 1

Definition: A man of a higher rank or position.

2. sir (noun) — sense 2

Definition: A respectful term of address to a man of higher rank or position, particularly

Example: Jeeves: Foreign travel often liberates emotions best kept in check, sir. The air of North America is notoriously stimulating in this regard, as witness the regrettable behavior of its inhabitants in 1776.
B. Wooster: Hm? What happened in 1776, Jeeves?
Jeeves: I prefer not to dwell on it, if it's convenient to you, sir.

3. sir (noun) — sense 3

Definition: A respectful term of address to a man of higher rank or position: to a knight or other low member of the peerage.

Example: Just be careful. He gets whingy now if you don't address him as Sir John.

4. sir (verb) — sense 4

Definition: To address another individual using "sir".

Example: Sir, yes, sir! —Don't you sir me, private! I work for a living!