n. [ Gr. no`hma the understanding + ta`chos swiftness + -graph. ] An instrument for determining and registering the duration of more or less complex operations of the mind. Dunglison. [ 1913 Webster ]
n. [ Gr. ta`chos speed + -graph. ] A recording or registering tachometer; also, its autographic record. [ Webster 1913 Suppl. ]