semiotics n.

1620s, "of symptoms, relating to signs of diseases," from Latinized form of Greek sēmeiōtikos "significant, portending, worth marking," also "observant of signs," adjective form of sēmeiosis "indication," from sēmeioun "to signal, to interpret a sign," from sēmeion "a sign, mark, token," from sēma "sign" (see semantic). Its use in linguistics and psychology, "of or pertaining to the use of signs," is by 1923. Related: Semiotical (1580s).

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.