1854, "a spider," from French arachnide (1806) or Modern Latin Arachnida (plural), the zoological name for the class of arthropods including spiders, scorpions, and mites, introduced as a class-name 1815 by French biologist Jean Baptiste Pierre Antoine de Monet de Lamarck, from Latinized form of Greek arakhnē (fem.) "spider; spider's web," which probably is cognate with Latin aranea "spider, spider's web," from aracsna, which is of unknown origin.

The Latin word could be a borrowing of the Greek one, or both could be from a common root. Beekes writes, "As the word looks non-IE and since it is limited to these two languages, it is probably a borrowing." Latin aranea is the source of common words for "spider" in French (araignée, Old French araigne), Spanish (araña), Italian (aragna), etc. It also was borrowed in Old English as renge "spider;" Middle English had araine "spider" (late 14c., from Old French), which survived in dialect as arain, noted in John Ray's "Collection of English Words" (1768) as a Nottinghamshire word for "the larger kind of spiders." Also compare araneology.

Earlier noun forms were arachnidian (1828), arachnidan (1843). As adjectives, arachnidean (1853), arachnidian (1854), arachnidial (1877), arachnidal (1850), arachnidous (1833) have been used.

"a load, that which is borne or carried," Old English byrðen "a load, weight, charge, duty;" also "a child;" from Proto-Germanic *burthinjo- "that which is borne" (source also of Old Norse byrðr, Old Saxon burthinnia, German bürde, Gothic baurþei), from PIE root *bher- (1) "to carry," also "to bear children."

The shift from -th- to -d- began early 12c. (compare murder (n.), rudder, afford). Archaic burthen is occasionally retained for the specific sense of "capacity of a ship." Beast of burden is from 1740. Burden of proof (Latin onus probandi) "obligation on one party in an action to establish an alleged fact by proof" is recorded from 1590s.

fourth letter of the Roman alphabet, from Greek delta, from Phoenician and Hebrew daleth, pausal form of deleth "door," so called from its shape.

The form of the modern letter is the Greek delta (Δでるた) with one angle rounded. As the sign for "500" in Roman numerals, it is said to be half of CIƆ, which was an early form of M, the sign for "1,000." 3-D for "three-dimensional" is attested from 1952.

Unetymological -d- is the result of a tendency in English and neighboring languages, perhaps for euphony, to add -d- to -n-, and especially to insert or swap a -d- sound when -l- or -r- follow too closely an -n-.

Compare sound (n.1), gender (n.), thunder (n.), spindle, kindred, strand (n.2) "fiber of rope," dialectal rundel, rundle for runnel. Swound was a form of swoun (swoon) attested from mid-15c, and used by Malory, Spenser, Lyly, Middleton, Beaumont & Fletcher. Among the words from French are powder (n.), meddle, tender (adj.), remainder, also riband, jaundice. It is less evident in spider (an agent noun from the Germanic *spin- root), and perhaps explains lender in place of loaner.

"a large waterfowl proverbially noted, I know not why, for foolishness" [Johnson], Old English gos "a goose," from Proto-Germanic *gans- "goose" (source also of Old Frisian gos, Old Norse gas, Old High German gans, German Gans "goose"), from PIE *ghans- (source also of Sanskrit hamsah (masc.), hansi (fem.), "goose, swan;" Greek khen; Latin anser; Polish gęś "goose;" Lithuanian žąsis "goose;" Old Irish geiss "swan"), probably imitative of its honking.

Geese are technically distinguished from swans and from ducks by the combination of feathered lores, reticulate tarsi, stout bill high at the base, and simple hind toe. [Century Dictionary]

Spanish ganso "goose" is from a Germanic source. Loss of "n" sound before "s" is normal in English (compare tooth). Plural form geese is an example of i-mutation. Meaning "simpleton, silly or foolish person" is from early 15c. To cook (one's) goose is attested by 1845, of unknown origin; attempts to connect it to Swedish history and Greek fables are unconvincing. Goose-egg "zero" is attested by 1866 in baseball slang, from being large and round. The goose that lays golden eggs (15c.) is from Aesop.

"unlawful killing of another human being by a person of sound mind with premeditated malice," c. 1300, murdre, earlier morþer, from Old English morðor (plural morþras) "secret killing of a person, unlawful killing," also "mortal sin, crime; punishment, torment, misery," from Proto-Germanic *murthran (source also of Goth maurþr, and, from a variant form of the same root, Old Saxon morth, Old Frisian morth, Old Norse morð, Middle Dutch moort, Dutch moord, German Mord "murder"), from suffixed form of PIE root *mer- "to rub away, harm" (also "to die" and forming words referring to death and to beings subject to death).

The spelling with -d- probably reflects influence of Anglo-French murdre, from Old French mordre, from Medieval Latin murdrum, which is from the Germanic word. A parallel form murther persisted into 19c.

In Old Norse, custom distinguished morð "secret slaughter" from vig "slaying." The former involved concealment, or slaying a man by night or when asleep, and was a heinous crime. The latter was not a disgrace, if the killer acknowledged his deed, but he was subject to vengeance or demand for compensation.

Mordre wol out that se we day by day. [Chaucer, "Nun's Priest's Tale," c. 1386]

Weakened sense of "very unpleasant situation" is from 1878. Inverted slang sense of "something excellent or terrific" is by 1940. As the name of a parlor or children's game, by 1933.

mid-15c. (late 12c. as a surname), a variation or alteration of Middle English rother, from Old English roðor "paddle, oar," from Proto-Germanic *rothru- (source also of Old Frisian roðer, Middle Low German roder, Middle Dutch roeder, Dutch roer, Old High German ruodar, German Ruder "oar"), from *ro- "steer" (from PIE root *ere- "to row") + suffix *-þra, used to form neutral names of tools.

The original sense is obsolete. The meaning "broad, flat piece of wood attached to the stern of a boat and guided by a tiller for use in steering" is from c. 1300. For shift of -th- to -d- compare burden (n.1), murder (n.); simultaneous but opposite movement turned -d- to -th- in father (n.), etc.

Middle English toth "human or animal tooth," from Old English toð (plural teð), from Proto-Germanic *tanthu- (source also of Old Saxon, Danish, Swedish, Dutch tand, Old Norse tönn, Old Frisian toth, Old High German zand, German Zahn, Gothic tunþus), from PIE root *dent- "tooth."

Plural teeth is an instance of i-mutation. The loss of -n- before spirants is regular in Old English, Old Frisian, and Old Saxon: compare goose (n.), five, mouth (n.). Also thought, from stem of think; couth from the stem of can (v.1); us from *uns.

As "appetite, bodily desire" from late 14c. (as in colt's tooth, sweet tooth, dry tooth "thirst," toothsome, and compare figurative use of palate). Application to tooth-like parts (of saws, combs, etc.) is from late 14c.

Tooth and nail "with biting and scratching, with nails and teeth," hence "viciously, furiously" is from early 14c. (as nayles and teþ). To be armed to the teeth is from c. 1300. The tooth-fairy is attested from 1964.

"a small spider, a baby spider," 1842, from spider + -ling.

"worker on tall buildings, steeplejack," 1954; see spider (n.) + man (n.). The Marvel comics Spider-Man crime-fighting character was introduced in August 1962.

1823, said to have been discovered on the coast of the Pacific northwest of North America during Cook's third expedition and so named by the sailors, "from its striking resemblance to a large spider when it first appears above the surface, before the stem begins to rise from the spherical arrangement of the leaves, or the flagellae begin to creep to any distance from among them to the soil around" [Peter Sutherland, "Journal of a Voyage in Baffin's Bay," 1852]; from spider + plant (n.).