Etymology of Sinister and Dexterity

The left is sinister, the right is righteous, and the Etymology of Sinisterness and Dexterity!

etymology of sinister

«early 15c., “prompted by malice or ill-will, intending to mislead,” from Old French senestre, sinistre “contrary, false; unfavorable; to the left” (14c.), from Latin sinister “left, on the left side” (opposite of dexter), of uncertain origin. Perhaps meaning properly “the slower or weaker hand” [Tucker], but Klein and Buck suggest it's a euphemism (see left (adj.)) connected with the root of Sanskrit saniyan “more useful, more advantageous.” With contrastive or comparative suffix -ter, as in dexter (see dexterity).»

[etymology of sinister https://www.etymonline.com/word/sinister]

etymology of dexterity

« 1520s, from Middle French dexterité (16c.), from Latin dexteritatem (nominative dexteritas) “readiness, skillfulness, prosperity,” from dexter “skillful,” also “right (hand)” (source of Old French destre, Spanish diestro, etc.), from PIE root *deks- “on the right hand,” hence “south” to one facing east (cognates: Sanskrit daksinah “on the right hand, southern, skillful;” Avestan dashina- “on the right hand;” Greek dexios “on the right hand,” also “fortunate, clever;” Old Irish dess “on the right hand, southern;” Welsh deheu; Gaulish Dexsiva, name of a goddess of fortune; Gothic taihswa; Lithuanian desinas; Old Church Slavonic desnu, Russian desnoj). The Latin form is with the comparative suffix -ter, thus meaning etymologically “the better direction.” Middle English dester meant “right hand,” and in heraldry dexter means “on the right side.”»

[etymology of dexterity https://www.etymonline.com/word/dexterity]

and from which, righteousness sprang forth.

That's right.

And “right” basically came from meaning of “straight”, and ultimately “right hand”, the stronger hand.

righteous (adj.)

early 16c. alteration of rightwise, from Old English rihtwis, from riht (see right) + wis “wise, way, manner” (see wise (adj.)). Suffix altered by influence of courteous, etc. Meaning “genuine, excellent” is 1942 in jazz slang. Related: Righteously.

[etymology of righteousness https://www.etymonline.com/word/righteousness]

right (n.)

Old English riht (West Saxon, Kentish), reht (Anglian), “that which is morally right, duty, obligation,” also “rule of conduct; law of a land;” also “what someone deserves; a just claim, what is due; correctness, truth; a legal entitlement, a privilege,” from the root of right (adj.1). Meaning “the right” (as opposed to the left) is from mid-13c.; political use from 1825. From early 14c. as “a right action, a good deed.” Meaning “a blow with the right fist” is from 1898. The phrase to rights “at once, straightway” is 1660s, from sense “in a proper manner” (Middle English).

right (adj.1)

“morally correct,” Old English riht “just, good, fair; proper, fitting; straight, not bent, direct, erect,” from Proto-Germanic *rekhtaz (source also of Old Frisian riucht “right,” Old Saxon reht, Middle Dutch and Dutch recht, Old High German reht, German recht, Old Norse rettr, Gothic raihts), from PIE root *reg- “move in a straight line,” also “to rule, to lead straight, to put right” (see regal; source also of Greek orektos “stretched out, upright;” Latin rectus “straight, right;” Old Persian rasta- “straight, right,” aršta- “rectitude;” Old Irish recht “law;” Welsh rhaith, Breton reiz “just, righteous, wise”).

Compare slang straight (adj.1) “honest, morally upright,” and Latin rectus “right,” literally “straight,” Lithuanian teisus “right, true,” literally “straight.” Greek dikaios “just” (in the moral and legal sense) is from dike “custom.” As an emphatic, meaning “you are right,” it is recorded from 1580s; use as a question meaning “am I not right?” is from 1961. The sense in right whale is “justly entitled to the name.” Right stuff “best human ingredients” is from 1848, popularized by Tom Wolfe's 1979 book about the first astronauts. Right of way is attested from 1767. Right angle is from late 14c.

right (adj.2)

“opposite of left,” early 12c., riht, from Old English riht, which did not have this sense but meant “good, proper, fitting, straight” (see right (adj.1)). The notion is of the right hand as the “correct” hand. The usual Old English word for this was swiþra, literally “stronger.” “The history of words for ‘right’ and ‘left’ shows that they were used primarily with reference to the hands” [Buck]. Similar sense evolution in Dutch recht, German recht “right (not left),” from Old High German reht, which meant only “straight, just.”

The usual PIE root (*dek-) is represented by Latin dexter (see dexterity). Other derivations on a similar pattern to English right are French droit, from Latin directus “straight;” Lithuanian labas, literally “good;” and Slavic words (Bohemian pravy, Polish prawy, Russian pravyj) from Old Church Slavonic pravu, literally “straight,” from PIE *pro-, from root *per- (1) “forward, through” (see per).

The political sense of “conservative” is first recorded 1794 (adj.), 1825 (n.), a translation of French Droit “the Right, Conservative Party” in the French National Assembly (1789; see left (adj.)).

[etymology of right https://www.etymonline.com/word/right]

“ambivalence” is from “ambi” (both) and “valence” (strong). And it's a late word from 1924, from psychology.

ambivalence (n.)

“simultaneous conflicting feelings,” 1924 (1912 as ambivalency), from German Ambivalenz, coined 1910 by Swiss psychologist Eugen Bleuler (1857-1939) on model of German Equivalenz “equivalence,” etc., from Latin ambi- “both” (see ambi-) + valentia “strength,” abstract noun from present participle of valere “be strong” (see valiant). A psychological term that by 1929 had taken on a broader literary and general sense.

ambivalent (adj.)

1916, originally a term in psychology; back-formation from ambivalence. In general use by 1929.

[etymology of ambivalence https://www.etymonline.com/word/ambivalence]