"quadrilateral whose opposite sides are parallel," 1560s, from French parallélogramme (1550s) and directly from Late Latin parallelogrammum, from Greek parallelogrammon noun use of a neuter adjective meaning "bounded by parallel lines," from parallelos (see parallel) + stem of graphein "to write" (see -graphy). Related: Parallelogrammic; parallelogramical.
geometric figure, "oblique-angled equilateral parallelogram," 1570s, from French rhombe, from Latin rhombus "a magician's circle," also a kind of fish, which in Late Latin took on also the geometric sense. This is from Greek rhombos "circular movement, spinning motion; spinning-top; magic wheel used by sorcerers; tambourine;" also "a geometrical rhomb," also the name of a flatfish.
Watkins has this from rhembesthai "to spin, whirl," from PIE *wrembh-, from *werbh- "to turn, twist, bend" (source also of Old English weorpan "to throw away"), from root *wer- (2) "to turn, bend" (see versus). But Beekes connects rhombos to rhembomai "to go about, wander, roam about, act random," despite this being attested "much later," a word of no clear etymology.
In general use in reference to any lozenge-shaped object. Related: Rhombic.
1838, American English, apparently originally the name of some kind of alcoholic drink, of unknown origin. It has joined that class of words (such as dingus, doohickey, gadget, gizmo, thingumabob) which are conjured up to supply names for items whose proper names are unknown or not recollected. Used at various periods for "money," "a professional tramp," "a muffin," "male genitalia," "a Chinese," "an Italian," "a woman who is neither your sister nor your mother," and "a foolish person in authority." Popularized in sense of "foolish person" by U.S. TV show "All in the Family" (1971-79), though this usage dates from 1905. In typography, by 1912 as a printer's term for ornament used in headline or with illustrations.
About 10:30 o'clock there was a snap of breaking metal, and the machine was stopped. It was discovered that the gilderfluke had come into contact with the dudad which operates the dingus on the diaphason, thereby letting the Johnson bar oscillate as it were between Alpha and Omega, thus preventing the dingbat from percolating the perihelion of the gazabo, and causing the dofunny on the parallelogram to drop into oblivion. [from an Illinois newspaper's account of a production delay caused by a Linotype machine breakdown, reprinted in Inland Printer, Chicago, February 1903]