"moved or played by means of air; of or pertaining to air or gases," 1650s, from Latin pneumaticus "of the wind, belonging to the air," from Greek pneumatikos "of wind or air" (which is attested mainly as "of spirit, spiritual"), from pneuma (genitive pneumatos) "the wind," also "breath" (see pneuma). Earlier was pneumatical (c. 1600). The pneumatic-dispatch tube was so called by 1859 (in Paris, pneumatique).
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.
<a href="https://www.etymonline.com/word/pneumatics">Etymology of pneumatics by etymonline</a>
Harper, D. (n.d.). Etymology of pneumatics. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/pneumatics