After receiving his Ph.D. at Johns Hopkins and pursuing further study at the University of Berlin, he joined the faculty in 1909. He began teaching German to freshmen and sophomores, and soon was teaching Gothic, old Norse, Sanskrit, Lithuanian, and his famous course in linguistic science to graduate students.
A specialist in Lithuanian philology, he demonstrated in one of his major publications the relationship between Lithuanian and other Indo-European languages. In another important book he located the original home of the Indo-Europeans in eastern central Europe. As chief etymologist for Webster's New International Dictionary, with the assistance of seventy other scholars he revised the etymologies of over half a million words. This monumental achievement brought him worldwide recognition as an authority on the etymology of the English language.
Bender was a founder of the Linguistic Society of America and president of the American Oriental Society. He was an honorary doctor of philology of the University of Lithuania, and was decorated by Lithuania for his assistance during her struggle for independence.
An amateur criminologist, he gave the state police expert help in their investigation of the Lindbergh kidnapping and other cases. His colleagues thought that, for him, tracking down criminals was as interesting as ``tracing the origin of obscure words to some remote corner of the world or dim period of antiquity.''
He conducted most of his classes and did most of his research at home, and when it was necessary for him to come to the campus he usually came by taxi. He was a tireless worker with an amazing capacity for concentrated work. It was not unusual for passers-by to observe the light in his study at 120 FitzRandolph Road burning long after midnight.
His colleagues praised him for his critical insight and his acumen and what, they said, was an even rarer quality, his creative imagination. ``His own joy in what he was doing, and his conviction of its importance, were contagious. To numberless students, he was an unsurpassed example of the teacher-scholar.''