oblige

Oblige shares some similarities with its close relative obligate, but there are also differences. Oblige derived via Middle English and Anglo-French from Latin obligare ("to bind to"), a combination of ob- ("to or toward") and ligare ("to bind"), whereas obligate descended directly from the past participle of obligare. Both oblige and obligate are frequently used in their past participle forms to express a kind of legal or moral constraint. Obligated once meant "indebted for a service or favor," but today it typically means "required to do something because the law requires it or because it is the right thing to do." Obliged is now the preferred term for the sense that Southern author Flannery O'Connor used in a 1952 letter: "I would be much obliged if you would send me six copies."