Hardwood sources are trees that are used to make furniture, flooring, and other wood products. TEAK, ELM, and OAK are all examples of hardwood sources. TEAK is a tropical hardwood tree with four letters in its name. ELM is a deciduous tree with three letters in its name. OAK is also a deciduous tree with three letters in its name. Elmtree is a seven-letter word for a type of ELM tree. Beechtree is a nine-letter word for a type of beech tree.