psychometrics (n.)

1854, "the alleged power possessed by some sensitive persons of reading the history of an object by handling it;" see psycho- + -metry. In reference to the measurement of the duration of mental states from 1879. Related: Psychometric; psychometrical; psychometrist.

in the names of sciences or disciplines (acoustics, aerobics, economics, etc.), a 16c. revival of the classical custom of using the neuter plural of adjectives with Greek -ikos "pertaining to" (see -ic) to mean "matters relevant to" and also as the titles of treatises about them. Subject matters that acquired their English names before c. 1500, however, tend to be singular in form (arithmetic, logic, magic, music, rhetoric). The grammatical number of words in -ics (mathematics is/mathematics are) is a confused question.