headmastership n the position of headmaster Usage(s) Soon after he began teaching at the school in 1897, he coached the baseball team, an office which he kept up for eleven years of his headmastership. Endicott Peabody, a living legend at 87, retired from Groton's headmastership in 1940to a new house just off the campus. In 1916 he went to Yale as professor of Latin, resigned three years later to accept the Lawrenceville headmastership.