ensign

Concise Oxford English Dictionary © 2008 Oxford University Press:
ensign /ˈɛnsʌɪn/

▶noun

• 1 a flag, especially a military or naval one indicating nationality.

• 2 the lowest rank of commissioned officer in the US and some other navies, above chief warrant officer and below lieutenant.

  ■ historical the lowest rank of commissioned infantry officer in the British army.

• 3 historical a standard-bearer.

– origin ME: from OFr. enseigne, from L. insignia (see insignia).