The Collaborative International Dictionary of English v.0.48:

Fo \Fo\ (f[=o]), n.
   The Chinese name of Buddha.
   [1913 Webster]

WordNet (r) 3.0 (2006):

FO
    n 1: an officer holding the rank of major or lieutenant colonel
         or colonel [syn: field-grade officer, field officer,
         FO]

V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

FO
       Fiber Optic


The Free On-line Dictionary of Computing (30 December 2018):

fo

    The country code for the Faroe Islands.

   (1999-01-27)