Defn: See Perkinism.
TRACTOR SCREW; TRACTOR PROPELLER
Tractor screw or propeller. (Aviation)
Defn: A propeller screw placed in front of the supporting planes of an aëroplane instead of behind them, so that it exerts a pull instead of a push. Hence, Tractor monoplane, Tractor biplane, etc.
TRACTORY Tract"o*ry, n. Etym: [L. tractorius of drawing, fr. trahere, tractum, to draw.] (Geom.)
Defn: A tractrix.
TRACTRIX
Tract"rix, n. Etym: [NL. See Tractor.] (Geom.)
Defn: A curve such that the part of the tangent between the point of tangency and a given straight line is constant; — so called because it was conceived as described by the motion of one end of a tangent line as the other end was drawn along the given line.
TRAD
Trad, obs.
Defn: imp. of Tread. Chaucer.
TRADE Trade, n. Etym: [Formerly, a path, OE. tred a footmark. See Tread, n. & v.]