factor XIII
— Noun
– English
～ in the clotting of blood thrombin catalyzes factor XIII into its active form (fibrinase) which causes fibrin to form a stable clot
family Xiphiidae
— Noun
– English
～ comprising the common swordfishes
family Xylariaceae
— Noun
– English
～ family of fungi characterized by dark brown to black spores
family Xyridaceae
— Noun
– English
～ plants of tropical to temperate regions; usually in wet places