en·sign 
(ĕnsən, -sīn′)
(ĕnsən, -sīn′)n.
1. A national flag displayed on ships and aircraft, often with the special insignia of a branch or unit of the armed forces.
2. A standard or banner, as of a military unit.
3. (ĕnsən)
a. A commissioned rank in the US Navy or Coast Guard that is below lieutenant junior grade.
b. One who holds this rank.
4. A badge, emblem, or token of power or authority.
[Middle English ensigne, from Old French enseigne, from Latin īnsignia, insignia; see INSIGNIA.]