13-Letter Words Containing: X,T,H

• Any of various typically yellow-brown dinoflagellates (originally grouped as genus Zooxanthella) now assigned to the genera Symbiodinium and Amphidinium, notably found in coral reefs.

• To introduce a hydroxyl group into a compound

• extinct primitive toothed bird of the Jurassic period having a long feathered tail and hollow bones; usually considered the most primitive of all birds