Middle English shaken, from Old English sceacan "move (something) quickly to and fro, cause to move with quick vibrations; brandish; move the body or a part of it rapidly back and forth;" also "go, glide, hasten, flee, depart" (as in sceacdom "flight"); also intransitive, of persons or parts of the body, "to tremble" especially from fever, cold, fear (class VI strong verb; past tense scoc, past participle scacen).

This is reconstructed to be from Proto-Germanic *skakanan "to shake, swing," also "to escape" (source also of Old Norse, Swedish skaka, Danish skage "to shift, turn, veer"). There are said to be no certain cognates outside Germanic, but some sources suggest a PIE root *(s)keg- "to jump, to move" (compare Sanskrit khaj "to agitate, churn, stir about," Old Church Slavonic skoku "a leap, bound," Welsh ysgogi "move"). Also compare shock (n.1).

Of the ground in earthquakes, c. 1300. The meaning "seize and shake" (someone or something else) is from early 14c. From late 14c. in reference to mixing ingredients, etc., by shaking a container. The meaning "weaken, impair" in any respect is from late 14c. on the notion of "make unstable." The meaning "rid oneself of by abrupt twists" is from c. 1200; the modern colloquial use for "get rid of, cast off, abandon" (by 1872, American English) is likely a new extension on the notion of "throw off by a jolting or abrupt action," perhaps with horses in mind. The verb also was used in Middle English as "evade" responsibility, etc.

To shake hands "greet or salute by grasping one another's hands" dates from 1530s. Colloquial shake a (loose) leg "hurry up" is recorded by 1904; to shake a heel (sometimes foot) is an old or provincial way to say "dance" (1660s); to shake (one's) elbow (1620s) meant "to gamble at dice." In 16c.-18c. English, shake (one's) ears was "bestir oneself," an image of animal awakenings. The phrase more _____ than you can shake a stick at "more than you can count" is attested from 1818 (Lancaster, Pa., "Journal"), American English. To shake (one's) head "move one's head from side to side as a sign of disapproval" is recorded from c. 1300.

"strip of wood forming the border of a field," 1570s, a respelling of Middle English shau, shaue "wood, forest, grove, thicket," from Old English sceaga "copse," cognate with North Frisian skage "farthest edge of cultivated land," Old Norse skage "promontory," and perhaps with Old English sceaga "rough matted hair" (see shag (n.)). The Old English word also is the source of the surname Shaw (attested from late 12c.) in all its variations.

type of hickory noted for yielding the best hickory nuts, 1751, American English, from shag (n.) + bark (n.1). The name was earlier given to a type of West Indian tree (1690s).

"unkempt; having rough, coarse, long hair," 1580s, from shag (n.) + -y (2). Related: Shaggily; shagginess. Earlier was shagged, from Old English sceacgede "hairy;" compare Old Norse skeggjaðr, Danish skægget "bearded." The shaggy-dog story as a type of absurd joke built into a long, tedious story, is attested from 1943 and was a fad in the mid-40s. The origin of the phrase may be in vaudeville; the most-often cited original example involves an Englishman who offers a reward for a lost shaggy dog, an enterprising American who, with great difficulty, tracks him down and offers a shaggy dog that he claims is the one, and his curt reception: "Not that shaggy." But the story does not seem to be older than the phrase.

"thick mass of hair," 1819, from earlier shock (adj.) "having thick hair" (1680s), and a 17c. noun meaning "lap-dog having long, shaggy hair" (1630s, also shock-dog), from shough (1590s), the name for this type of dog, which was said to have been brought originally from Iceland; the word is perhaps from the source of shock (n.2), or from an Old Norse variant of shag (n.). Shock-headed Peter was used in 19c. translations for German Struwwelpeter.