What does semper fi mean?

Question

i know it has something to do with the service or something like that.

Answer 1

Always faithful

Answer 2

Semper Fidelis is Latin for "Always faithful." Best known to Americans as the motto of the United States Marine Corps, this phrase has served as a slogan for many families and entities, in many countries, dating at least as far back as the 14th century.  

Answer 3

The first two responders are correct.  It is Latin for "Always Faithful" and is also the motto for the U. S. Marine Corps.  I think that motto is at least partially responsible for the idea, "Once a Marine, Always a Marine."  

Answer 4

Short for Semper Fidelis meaning always faithful

Its used by the Marines

Answer 5

It is short for semper fidelis, meaning always faithful.  It is generally used as a sign-off on a formal letter or perhaps a religious newsletter.