thermosetting plastic
/θm.υset.. plst.k/ noun a type of plastic which is heated while being shaped but which cannot be softened by reheating . If a piece of thermosetting plastic is hit hard enough, it breaks into pieces with straight sharp edges.
thick /θ.k/ adjective 1. of great or par-ticular extent between two surfaces . a 1cm thick steel bar . This sheet of alu-minium is not very thick. 2. with a large diameter . thick wire 3. dense . thick fog . thick cloud 4. of a consistency which does not flow easily . thick oil Opposite thin
thickness /θ.kn.s/ noun 1. the
extent between two surfaces . In mono-coque construction, there is no internal stiffening because the thickness of the skin gives strength and stability. 2. the extent of the diameter of a wire 3. the state or condition of being thick
thin /θ.n/ adjective 1. of small extent between two surfaces . a thin layer of paint 2. with a small diameter . thin
wire 3. not dense . thin mist . Altostra-tus cloud is thin enough for the sun to be dimly visible. 4. of a consistency which flows easily . thin oil Opposite thick
thinness /θ.nn.s/ noun 1. a small extent between two surfaces . The thin-ness of the material makes it unsuitable.
2. a small extent of the diameter of a wire 3. the state or condition of being thin
thorough /θr./ adjective complete
. All cabin crew must have a thorough knowledge of fire fighting equipment and procedures. . a thorough inspec-tion a very detailed, comprehensive inspection
THP abbreviation thrust horsepower three-letter group /θri let. rup/ noun three letters of the alpha-bet found together
three-point landing /θri p..nt lnd../ noun an aircraft landing in which the two main wheels of the land-ing gear and the nosewheel or tailwheel touch the ground at the same time
threshold /θre.h.υld/ noun the
beginning of the part of the runway, usable for landing . Runway visual range is obtained by an observer stand-ing at the side of the runway in the vicinity of the threshold counting the number of markers or lights visible along the side of the runway.
COMMENT: The threshold is marked with a single white line on visual runways or by eight parallel white lines arranged longitudinally in two groups of four each side of the runway centreline for runways with instrument approach/landing facilities.

throttle /θr.t(.)l/ noun 1. a throttle lever 2. a throttle valve . verb . to throttle back to reduce engine power .
Throttle back to increase the rate of descent.
COMMENT: The verbs ‘open’ or ‘advance’ (= to increase engine power) and ‘close’ or ‘throttle back’ (= to decrease engine power) are frequently used by instructors to explain the required movement of the throttle lever in the cockpit.