analogos (ἀνάλογος) “proportionate” (also “analogous”), from ana (ἀνά) “up to” + logos (λόγος) “ratio, proportion, word, reason, account”.

arithmos (ἀριθμός) “number”

asymmetros (ἀσύμμετρος) “asymmetric, incommensurable, disproportionate, unfit”

diametros (διάμετρoς) διαμετρoς “diametric, diameter, diagonal, axis” from dia (διά) “through” + metron (μέτρον) “measure”

elleipsis (ἔλλειψις) “a falling short, omission, deficiency”
From en (ἐν) “in”+ leipō (λεἰπω) “to leave”; together means “to leave in, leave behind."

geōmetria (γεωμετρία) “geometry” from gē (γῆ) “earth, land” + metron (μέτρον) “measure”
The name George comes from geōrgos (γεωργός) “farmer”

gōnia (γωνία) “corner or angle”

grammē (γραμμή) “line”
Related to graphō (γράφω) “to write, draw."

hexagōnon (ἑξάγωνον) “hexagon”

hypoteinousa (ὑποτείνουσα) “something stretched under, or subtended”; in geometry “hypotenuse,” from hypo (ὑπό) “under” + teinō (τείνω) “stretch, extend”

hyperbolē (ὑπερβολή) “a throwing beyond, an overshooting, excess”, in geometry “hyperbola” From hyper (ὑπέρ) “over” + ballō (βάλλω) “throw”; together means “overshoot."
The English word hyperbole also comes from this word in the sense of “excess”.

isos (ἴσoς) “equal”

isoskelēs or isoscelēs (ἰσoσκελής) “with equal legs, isosceles”
from skelos (σκέλος) “leg”

kōnos or cōnos (κῶνος) “pine-cone”, later “cone” in geometry. kentron or centron (κέντρον) “goad, spur, sting, or any sharp point”. In geometry originally the “fixed or
sharp point on a compass” Our word center comes from this word.

kyklos or cyclos (κύκλος) “circle, ring” sphaira (σφαῖρα) “ball, sphere”
Came to English via Latin sphaera or sphera.

kylindros or cylindros (κύλινδρος) “roller, cylinder”
From the Greek verb kulindō (κυλίνδω) “to roll”

mathēma(tos)(μάθημα, μάθηματος) “learning, knowledge”, more specifically “mathematics”
This subject originally included arithmetic, geometry, astronomy, and music theory.

mathēmatikos (μαθηματικός) “one fond of learning; mathematician”; among Pythagoreans “an advanced student”
Comes from the verb mathein (μαθεῖν) “to learn”

orthogōnion (ὀρθογώνιον) “rectangle” from orthos (ὀρθός) “straight, upright, right”

parallēlos (παράλληλος) “side by side”, in geometry “parallel”
From para (πάρα) “by, beside” + allēl- (ἄλληλ-) “each other."

parallēlogrammos (παραλληλόγραμμος) “parallelogram” from parallēlos (παράλληλος) and grammē (γραμμή).

parabolē (παραβολή) “comparison, juxta-position”; in geometry “application” or “parabola” From para (πάρα) “by, beside” + ballō (βάλλω) “throw; place”; together means “place besides.
The English word parable also comes from this word in the sense of “comparison”.

pentagōnon (πεντάγωνον) “pentagon”

prisma (πρίσμα) “something sawed”, in geometry “prism”
From the Greek verb priō (πρίω) “to saw."

pyramis (pyramidos) (πυραμίς, πυραμίδος) “pyramid” probably borrowed from Egyptian.
The Greeks used this term for the tetrahedron and the square base pyramid. We tend to use it mainly for the square based figure.

symmetros (σύμμετρος) “commensurate with, comensurable, proportionate, symmetric, in due measure, moderate” from syn (σύν) “with” + metron (μέτρον) “measure”

tetragōnon (τετράγωνον) “square”

trigōnon (τρίγωνον) “triangle”

stereos (στερεός) “solid, firm; three dimensional”