assimilated form of L. ad- to, before t, used in all modern words from Latin. In OF. ad-, at-, was reduced to a-, and so introduced into ME., but afterwards refashioned as at-, after L. spelling, both in Fr. and English, e.g., L. attingĕre, OF. ateindre, later atteindre, ME. ataindre, mod. attainder. The Eng. has also taken at- where Fr. retains the simple a-, as in OF. atorné, mod. atourné, ME. atorney, mod. attorney. The t was also erroneously doubled in various words in at- with prefix a- from other sources, as a(t)tame, a(t)tray, a(t)troke. See AD- pref.2
