The 90 degree angle between two perpendicular lines.
Roget 244:
angularity,
angularness†;
aduncity†;
angle,
cusp,
bend;
fold
etc.
258;
notch
etc.
257;
fork,
bifurcation.
elbow,
knee,
knuckle,
ankle,
groin,
crotch,
crutch,
crane,
fluke,
scythe,
sickle,
zigzag,
kimbo†,
akimbo.
corner,
nook,
recess,
niche,
oriel [Arch.],
coign†.
right angle
etc.
(perpendicular)
216.1,
212;
obliquity
etc.
217;
angle of 45 degrees,
miter;
acute angle,
obtuse angle,
salient angle,
reentering angle,
spherical angle.
angular measurement,
angular elevation,
angular distance,
angular velocity;
trigonometry,
goniometry;
altimetry†;
clinometer,
graphometer†,
goniometer;
theodolite;
sextant,
quadrant;
dichotomy.
triangle,
trigon†,
wedge;
rectangle,
square,
lozenge,
diamond;
rhomb,
rhombus;
quadrangle,
quadrilateral;
parallelogram;
quadrature;
polygon,
pentagon,
hexagon,
heptagon,
octagon,
oxygon†,
decagon.
pyramid,
cone.
Platonic bodies;
cube,
rhomboid;
tetrahedron,
pentahedron,
hexahedron,
octahedron,
dodecahedron,
icosahedron,
eicosahedron;
prism,
pyramid;
parallelopiped;
curb roof,
gambrel roof,
mansard roof.
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Roget 212:
verticality;
erectness
etc.
adj.;
perpendicularity
etc.
216.1;
right angle,
normal;
azimuth circle.
wall,
precipice,
cliff.
elevation,
erection;
square,
plumb line,
plummet.
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Dutch: rechte hoek
Polish: kąt prosty