Mid 19th century. Irregularly from classical Latin adīre to approach, to come into (an inheritance) + -ate, apparently after Dutch †adiëren, itself originally formed after aditie. Compare the older Dutch legal terms aangaan to accept (an inheritance), specific use (now disused) of aangaan to begin, to undertake, lit. ‘to go towards’ and aanvaarden to undertake, to take possession of, lit. ‘to travel towards’ (Middle Dutch anevaerden, aenvaerten).