c. 1300, "shake from fear, cold, etc.," from Old French trembler "tremble, fear" (11c.), from Vulgar Latin *tremulare (source also of Italian tremolare, Spanish temblar), from Latin tremulus "trembling, shaking, quaking," from tremere "to tremble, shiver, quake," from PIE *trem- "to tremble" (source also of Greek tremein "to shiver, tremble, to quake, to fear," Lithuanian tremiu, tremti "to chase away," Old Church Slavonic treso "to shake," Gothic þramstei "grasshopper"). A native word for this was Old English bifian. Related: Trembled; trembling. The noun is recorded from c. 1600.
c. 1200, shoderen, "tremble, quake, shiver, vibrate,," not found in Old English; possibly from Middle Dutch schuderen "to shudder," or Middle Low German schoderen, both frequentative forms from Proto-Germanic *skuth- "to shake." Related: Shuddered; shuddering.
1600, "at leisure, not occupied," from un- (1) "not" + past participle of employ (v.). Meaning "temporarily out of work" is from 1660s. There seems not to have been a verb *unemploy, but disemploy was used (1610s). The noun meaning "unemployed persons collectively" is from 1782.
No man has hired us
With pocketed hands
And lowered faces
We stand about in open places
And shiver in unlit rooms ...
[T.S. Eliot, from "Choruses from the Rock"]
before vowels seism-, word-forming element meaning "earthquake," from Greek seismos "a shaking, shock; an earthquake," also "an extortion" (compare colloquial shake (someone) down), from seiein "to shake, agitate, sway; to quake, shiver" from PIE root *twei- "to agitate, shake, toss; excite; sparkle" (source also of Sanskrit tvesati "to excite; to be excited, inflame, sparkle" and words in Avestan for "fears" and "fright, danger").
1843, "to seesaw," alteration of Middle English titter "move unsteadily," probably from a Scandinavian source akin to Old Norse titra "to shake, shiver, totter, tremble," from Proto-Germanic *ti-tra- (source also of German zittern "to tremble"). Meaning "move unsteadily, be on the edge of imbalance" is from 1844.
Noun teeter-totter "see-saw" is attested from 1871 (earlier simply teeter, 1855, and titter-totter in same sense is from 1520s). Totter (n.) "board swing" is recorded from late 14c.; see totter (v.), and compare see-saw.
late 14c., shruggen, "raise or draw up (the shoulders) with a sudden movement," a word of uncertain origin, perhaps connected to Danish skrugge "to stoop, crouch." From c. 1600 generally as an expression of doubt, indifference, etc., but it isn't clearly so in the earliest uses. It also could mean "to shrink, to shiver," as with cold (mid-15c.). Related: Shrugged; shrugging. Figurative use of shrug (something) off "be indifferent to" is by 1909.
late 14c., "causing terror, awe, or dread; frightful," from Old French terrible (12c.), from Latin terribilis "frightful," from terrere "fill with fear," from PIE root *tros- "to make afraid" (source also of Sanskrit trasanti "to tremble, be afraid," Avestan tarshta "scared, afraid," Greek treëin "to tremble, be afraid," Lithuanian trišėti "to tremble, shiver," Old Church Slavonic treso "I shake," Middle Irish tarrach "timid"). Weakened sense of "very bad, awful" is first attested 1590s.
"female monster with a petrifying look," late 14c., in Greek legend, any of the three hideous sisters, with writhing serpents for hair, whose look turned beholders to stone, from Greek Gorgones (plural; singular Gorgō) "the grim ones," from gorgos, of a look or gaze, "grim, fierce, terrible," later also "vigorous, lively," a word of unknown origin. Beekes' sources reject the proposed connections to Old Irish garg "raw, wild," Old Church Slavonic groza "shiver," Armenian karcr "hard."
Transferred sense of "terrifyingly ugly person" is from 1520s. Their names were Medusa, Euryale, and Stheino, but when only one is mentioned, Medusa usually is meant. Slain by Perseus, her head was fixed on the aegis of Athena.