Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
admĭnistrātor, ōris, m. [administro], lit., he that is near to aid, assist, etc., in the care of a thing; hence, a manager, conductor (cf. administro): (imperator est) administrator quidam belli gerendi, Cic. de Or. 1, 48, 210: rerum civitatis, Dig. 3, 4, 10 al.