Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
‡ păcĭo, ōnis, f., a contract, covenant (ante-class. for pactio): pacionem antiqui dicebant, quam nunc pactionem dicimus: unde et pacisci adhuc et paco in usu remanet, Fest. p. 250 Müll. (perh. too, ap. Fest. s. v. nuptias, p. 170, instead of ratio we should read pacio, acc. to the conject. of Dac. on the preced. passage).