Fo flywort • foal · · · Info · Definitions · Synonyms · Characters · · Fo · · Text Latin · · Script 2 · · Length Definitions · · · (noun) an officer holding the rank of major or lieutenant colonel or colonel. Synonyms: field-grade officer, field officer, FO. · · Noun Definition 1 Synonyms · · · field-grade officer · · Synonym 1 field officer · · Synonym 2 Characters · · F latin capital letter f U+0046 o latin small letter o U+006F