fortification

n.防御工事，尤指堡垒、要塞城墙等

formless, formlessly, formula, formulaic, formulate, formulation, fornicate, fornication, forsake, forsaken, forseeable, forswear, forsythia, fort, forte, forth, forthcoming, forthright, forthwith, fortieth, fortified wine, fortify, fortissimo, fortitude, fortnight, fortnightly, FORTRAN (also Fortran), fortress, fortuitous, fortuity, fortunate, fortunately, fortune, fortune cookie, fortune-hunter, fortune-teller, forty, forty-five (also 45), forum, forward,