Etymology
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rhomboid (n.)

in geometry, "a non-equilateral oblique parallelogram," 1560s, from French rhomboide or directly from Late Latin rhomboides, from Greek rhomboeides "rhomboidal; a rhomboid;" see rhomb + -oid. Related: Rhomboidal. As an adjective, "having a form like a rhomb," from 1690s.

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vertex (n.)
1560s, "the point opposite the base in geometry," from Latin vertex "highest point," literally "the turning point," originally "whirling column, whirlpool," from vertere "to turn" (from PIE root *wer- (2) "to turn, bend"). Meaning "highest point of anything" is first attested 1640s.
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multilateral (adj.)

also multi-lateral, 1690s, in geometry, "having many sides," from multi- "many" + lateral (adj.). Figurative use, "many-sided," is by 1748. Meaning "pertaining to three or more countries" is from 1802 (based on bilateral). Related: Multilaterally.

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parabolic (adj.)

mid-15c., parabolik, "figurative, allegorical, of or pertaining to a parable or a parabole," from Medieval Latin parabolicus, from late Greek parabolikos "figurative," from parabolē "comparison" (see parable). In geometry, "of or pertaining to a parabola," by 1702 (see parabola). Related: Parabolical.

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analyst (n.)
1650s, "one versed in algebraic analysis, mathematician skilled in algebraic geometry," from French analyste "a person who analyzes," from analyser, from analyse "analysis," from Medieval Latin analysis (see analysis). As a short form of psychoanalyst, attested from 1914; the one analyzed is an analysand (1933). Greek analyter meant "a deliverer."
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diameter (n.)

late 14c., in geometry, "chord of a circle or sphere which passes through its center; the length of a diameter," from Old French diametre, from Latin diametrus, from Greek diametros (gramme) "diagonal of a circle," from dia "across, through" (see dia-) + metron "a measure" (from PIE root *me- (2) "to measure").

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polygon (n.)

in geometry, "a plane figure with numerous angles," 1570s, from Late Latin polygonum, from Greek polygōnon, noun use of neuter of adjective polygōnos "many-angled," from polys "many" (from PIE root *pele- (1) "to fill") + -gōnos "angled," from gōnia "angle, corner" (from PIE root *genu- (1) "knee; angle"). Related: Polygonal.

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second (n.1)
"one-sixtieth of a minute of degree," also "sixtieth part of a minute of time," late 14c. in geometry, from Old French seconde, from Medieval Latin secunda, short for secunda pars minuta "second diminished part," the result of the second division of the hour by sixty (the first being the "prime minute," now called the minute), from Latin secunda, fem. of secundus "following, next in time or order" (see second (adj.)). The second hand of a clock is attested from 1759.
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octagon (n.)

in geometry, "a plane figure having eight angles and eight sides," 1650s, from Latin octagonos, from Greek oktagōnos, literally "eight-angled, eight-cornered," from okta- combining form of okto "eight" (see eight) + gōnia "angle," which is related to gony "knee" (from PIE root *genu- (1) "knee; angle"). Also octogon (1650s), from French octogone.

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intersection (n.)

1550s, "act or fact of crossing," from French intersection (14c.) and directly from Latin intersectionem (nominative intersectio) "a cutting asunder, intersection," noun of action from past-participle stem of intersecare "intersect, cut asunder," from inter- "between" (see inter-) + secare "to cut" (from PIE root *sek- "to cut"). In English originally a term in geometry; meaning "crossroads, a place of crossing" is from 1864. Related: Intersectional.

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