The word 榆树 is formed by combining the character 榆, meaning elm, with 树, meaning tree. 榆 is a phonetic-semantic character where 木 provides the meaning of wood or tree and 俞 indicates pronunciation, while 树 similarly uses 木 for meaning and 对 for sound. In combination, 榆 specifies the type of tree and 树 denotes the general category, resulting in the term for elm tree.