Word Origin & History
tangent (adj.)
1594, "meeting at a point without intersecting," from L. tangentem (nom. tangens), prp. of tangere "to touch," from PIE base *tag- "to touch, to handle" (cf. L. tactus "touch," Gk. tetagon "having seized," O.E. þaccian "stroke, strike gently"). First used by Dan. mathematician Thomas Fincke in "Geomietria Rotundi" (1583). The noun also is attested from 1594; extended sense of "slightly connected with a subject" is first recorded 1825. Tangential is recorded from 1630; fig. sense of "divergent, erratic" is from 1787.