noun

• (archaic) Buddha, in the context of Chinese Buddhism.
• (paper, printing) Abbreviation of folio., page and book size (10"-12.5" x 15"-20"). [A leaf of a book or manuscript.]
• (aviation) Initialism of first officer. [The copilot of an aircraft.]
• Initialism of field officer. [A (para)military commissioned officer who holds a field grade, ranking under general officers but above lower grades and fit to command medium-size units on the field, such as a battalion or regiment; or a non-army equivalent in rank.]
• (logic, computer science) Initialism of first-order logic. [(logic) A formal deductive system extended from propositional logic with the possibility to quantify over individuals of the domain of discourse.]