linear
one-dimensional
arrowlike
dead straight
direct
even
flat
horizontal
in a line
level
lineal
rectilineal
right
ruler-straight
smooth
straight
straight-cut
straight-front
straight-side
streamlined
true
unbending
unbent
unbowed
unbroken
uncurved
undeflected
undeviating
undistorted
uninterrupted
unswerving
unturned
upright
vertical
rectangle
rectangular
contactless
court
cross-wrapped
equilateral
etheric
flat-roofed
four-sided
hyperbolic
luminiferous
mud-walled
multi-axis
ninety-degree
nonpolar
octahedral
straight-line
subsonic
torsional
uncorruptible