late 14c., progressioun, "action of moving from one condition to another," from Old French progression and directly from Latin progressionem (nominative progressio) "a going forward, advancement, growth, increase," noun of action from past-participle stem of progredi "go forward," from pro "forward" (see pro-) + gradi "to step, walk," from gradus "a step" (from PIE root *ghredh- "to walk, go"). The musical sense of "an advance from one note to another" or later one chord to another is by c. 1600. Related: Progressional.

1620s, "pertaining to geometry," shortened form of geometrical (q.v.). In reference to a style of ancient Greek pottery decoration characterized by straight lines and angles, and the associated culture, 1902.

in mathematics, 1941, probably from isometric (q.v.) on the model of geometry/geometric.

1826 as a type of geometric figure, from hexa- + -gram. I Ching sense attested from 1804.

slightly earlier and more classical form of rhomb (q.v.), 1560s, from Late Latin rhombus, in the geometric sense.

also semisolid, "half-solid, very viscous," 1803, from semi- + solid (adj.). As a noun, "a surface composed of facets, like a geometric solid, but not closed," by 1891.

"geometric figure having seven sides and seven angles," 1550s, from Late Latin septangulus, from Latin sept- "seven" (see septi-) + angulus "angle" (see angle (n.)). Related: Septangular.

in geometry, "a solid having ten faces," 1828, from deca- "ten" + -hedron, from Greek hedra "seat, base, chair, face of a geometric solid," from PIE root *sed- (1) "to sit."  Related: Decahedral.

"solid having twelve faces," 1560s, from Greek dōdeka "twelve" (see dodeca-) + hedra "seat, base, chair, face of a geometric solid," from PIE root *sed- (1) "to sit." Related: Dodecahedral.

"the act of going backward," in reference to the apparent motion of planets in the sky, 1640s, noun of action, formed on model of progression, from Latin retrogressus, past participle of retrogradi "move backward" (see retrograde). Related: Retrogressional.