Old English þuma, from Proto-Germanic *thūman- (source also of Old Frisian thuma, Old Saxon, Old High German thumo, German Daumen, Dutch duim "thumb," Old Norse þumall "thumb of a glove"), literally "the stout or thick (finger)," from PIE *tum- "swell," from root *teue- "to swell." Unetymological spelling with -b (attested from late 13c.) is perhaps by influence of dumb; also compare limb (n.1).

In some of the IE languages there is a single word for "thumb," which is called the "big finger," like NE big toe. Many of the single words are of similar semantic origin, based on the notion of "stout, thick." [Buck]

Compare Greek megas daktylos "thumb," but Greek also had antikheir, literally "what is opposite the fingers." Italian pollice, French pouce are from Latin pollex, perhaps formed (on analogy of index) from pollere "to be strong."

Phrase rule of thumb attested by 1680s (the thumb as a rough measure of an inch is attested from c. 1500). To be under (someone's) thumb "be totally controlled by that person" is recorded from 1580s.

Thumbs up (1887) and thumbs down (1906) were said to be from expressions of approval or the opposite in ancient amphitheaters, especially gladiator shows, where the gesture decided whether a defeated combatant was spared or slain. But the Roman gesture was merely one of hiding the thumb in the hand or extending it. Perhaps the modern gesture is from the usual coachmen's way of greeting while the hands are occupied with the reins.

instrumental word-forming element, expressing "appliance, tool," from Old English -ol, -ul, -el, representing PIE *-lo- (see -ule). In modern English usually -le except after -n-. As in treadle, ladle, thimble, handle, spindle, girdle; also compare dialectal thrashle "flail, implement for thrashing," from Old English ðerscel, Middle English scrapel "instrument for scraping" (mid-14c.), etc.

Old English handle "a handle" (plural handla), formed from hand (n.) with instrumental suffix -el (1) indicating a tool in the way thimble was formed from thumb, spindle from spin, spindle from spin, ladle from lade, etc. The slang sense of "nickname" is first recorded 1870, originally U.S., from earlier expressions about adding a handle to (one's) name (1833), that is, a title such as Mister or Sir. To fly off the handle (1833) is a figurative reference to an ax head (to be off the handle "be excited" is recorded from 1825, American English). To get a handle on "get control of" is recorded by 1919.

late 13c., of persons, "submissive, respectful, lowly in manner, modest, not self-asserting, obedient," from Old French humble, umble, earlier umele, from Latin humilis "lowly, humble," literally "on the ground," from humus "earth" (from PIE root *dhghem- "earth"). From late 14c., of things, "lowly in kind, state, condition, or amount," also, of persons, "of low birth or rank." Related: Humbly.

Don't be so humble; you're not that great. [Golda Meir]

"agile, light and quick in motion, light-footed," c. 1300, nemel, from Old English næmel "quick to grasp, quick at taking" (attested but once), related to niman "to take," from Proto-Germanic *nemanan (source also of Old Saxon, Old Dutch, Gothic niman, Old Norse nema, Old Frisian nima, German nehmen "to take"), perhaps from PIE root *nem- "assign, allot; take."

With unetymological -b- attested from c. 1500 (compare limb (n.1)). Nimble-fingered is from 1620s; nimble-footed from 1590s; nimble-witted from 1610s. Related: Nimbleness. In 17c., English had nimblechaps "talkative fellow."

late 15c., originally nautical, "to fit (a ship) with necessary tackle, make (a ship) ready for sea," a word of obscure origin, probably from a Scandinavian source (compare Danish, Norwegian rigge "to equip," Swedish rigga "to rig, harness"), though these may be from English; perhaps ultimately from PIE *reig- "to bind."

The extended sense of "dress, fit out with, furnish with, provide" with something is by 1590s. That of "to adjust, put in condition for use, set in working order" is by 1620s.

The slang meaning "pre-arrange or tamper with results" is attested from 1938, perhaps a different word, from rig (n.) "a trick, swindle, scheme" (1775), earlier "sport, banter, ridicule" (1725), itself of unknown origin. Compare rig (n.2), which seems to approach some of these senses. To rig the market was a 19c. stock exchange phrase for "raise or lower prices artificially to one's private advantage." Also there is rig (v.) "ransack" from 1560s, likewise of unknown origin. Related: Rigged; rigging.

diminutive word-forming element, early 14c., from Old English -ling a nominal suffix (not originally diminutive), from Proto-Germanic *-linga-; attested in historical Germanic languages as a simple suffix, but probably representing a fusion of two suffixes: 1. that represented by English -el (1), as in thimble, handle; and 2. -ing, suffix indicating "person or thing of a specific kind or origin;" in masculine nouns also "son of" (as in farthing, atheling, Old English horing "adulterer, fornicator"), from PIE *-(i)ko- (see -ic).

Both these suffixes had occasional diminutive force, but this was only slightly evident in Old English -ling and its equivalents in Germanic languages except Norse, where it commonly was used as a diminutive suffix, especially in words designating the young of animals (such as gæslingr "gosling"). Thus it is possible that the diminutive use that developed in Middle English is from Old Norse.

early 13c., with unetymological -d-, from Old English spinel "small wooden bar used in hand-spinning," properly "an instrument for spinning," from stem of spinnan (see spin (v.)) + instrumental suffix -el (1) as in handle, treadle, thimble, etc. For the -d- also compare windel "wooden reel for winding yarn" (early 14c., perhaps from a derivative of Old Norse vindla "to wind up" or Middle Dutch windelen).

Related to Old Saxon spinnila, Old Frisian spindel, Old High German spinnila, German Spindel. As a type of something slender, it is attested from 1570s. As with distaff, sometimes formerly used as a metonym for "the female sex," as in Old English spinelhealf "female line of descent," distinguished from sperehealf "male line of descent."

*teuə-, also *teu-, Proto-Indo-European root meaning "to swell."

It forms all or part of: butter; contumely; creosote; intumescence; intumescent; protuberance; protuberant; psychosomatic; somato-; -some (3) "body, the body;" soteriology; Tartuffe; thigh; thimble; thousand; thole (n.); thumb; tumescent; tumid; tumor; truffle; tuber; tuberculosis; tumult; tyrosine.

It is the hypothetical source of/evidence for its existence is provided by: Avestan tuma "fat;" Greek tylos "callus, lump;" Latin tumere "to swell," tumidus "swollen," tumor "a swelling;" Lithuanian tukti "to become fat;" Lithuanian taukas, Old Church Slavonic tuku, Russian tuku "fat of animals;" Old Irish ton "rump."