Mawson, C.O.S., ed. (1870–1938). Roget’s International Thesaurus. 1922.

Class II. Words Relating to Space
Section III. Form
2. Special Form

246. Straightness.

   NOUN:STRAIGHTNESS, rectilinearity, rectilinearness; directness; inflexibility (stiffness) [See Hardness]; straight -, bee -, right -, direct- line; short cut.
   VERB:BE STRAIGHT &c. adj.; have no turning; not -incline, – bend, – turn, – deviate- to either side; go straight; steer for (direction) [See Direction].
  RENDER STRAIGHT, straighten, rectify; set -, put- straight; unbend, unfold, uncurl [See Convolution]; unravel [See Crossing], unwrap.
   ADJECTIVE:STRAIGHT; rectilinear, rectilineal; direct, even, right, true, in a line; virgate, unbent &c. v.; undeviating, unturned, undistorted, unswerving; straight-lined, straight as an arrow (direct) [See Direction]; inflexible [See Hardness].
  PERPENDICULAR, plumb, vertical, upright, erect.