four-ply

adj (of wool, wood, etc) having four strands or thicknesses （指毛线、 木材等）四股的, 四层的.

foully, foulness, found, foundation, foundation course, foundation-stone, foundations, founder, founder-member, founding father, foundling, foundry, fount, fountain, fountain-head, fountain-pen, four, four-, four-in-hand, four-letter word, four-poster, four-square, four-wheel drive, fourfold, foursome, fourteen, fourteenth, fourth, fowl, fowl pest, fox, fox-hunting, fox-terrier, foxglove, foxhole, foxhound, foxtrot, foxy, foyer, FPA,