tectonics (n.)

1650s, "of or relating to building or construction," from Late Latin tectonicus, from Greek tektonikos "pertaining to building," from tekton (genitive tektonos) "builder, carpenter, woodworker; master in any art (sculpture, metal-work, writing)," from PIE root *teks- "to weave," also "to fabricate." The geological sense, "pertaining to the structure of the earth's crust," is recorded from 1887.

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.