"truth, verity," late 12c., from a phonetic variant of Old English treowð "faithfulness, veracity, truth;" see truth, which is a doublet of this word. Restricted to Midlands and Northern England dialect after 16c., and to certain archaic phrases (such as plight one's troth). Also see betroth.
Entries linking to troth
Old English triewð (West Saxon), treowð (Mercian) "faith, faithfulness, fidelity, loyalty; veracity, quality of being true; pledge, covenant," from Germanic abstract noun *treuwitho, from Proto-Germanic treuwaz "having or characterized by good faith," from PIE *drew-o-, a suffixed form of the root *deru- "be firm, solid, steadfast." With Germanic abstract noun suffix *-itho (see -th (2)).
Sense of "something that is true" is first recorded mid-14c. Meaning "accuracy, correctness" is from 1560s. English and most other IE languages do not have a primary verb for "speak the truth," as a contrast to lie (v.). Truth squad in U.S. political sense first attested in the 1952 U.S. presidential election campaign.
At midweek the Republican campaign was bolstered by an innovation—the "truth squad" ..., a team of senators who trailed whistle-stopping Harry Truman to field what they denounced as his wild pitches. [Life magazine, Oct. 13, 1952]
Let [Truth] and Falsehood grapple; who ever knew Truth put to the worse, in a free and open encounter. [Milton, "Areopagitica," 1644]
also *dreu-, Proto-Indo-European root meaning "be firm, solid, steadfast," with specialized senses "wood," "tree" and derivatives referring to objects made of wood.
It forms all or part of: betroth; Dante; dendrite; dendro-; dendrochronology; dour; Druid; drupe; dryad; dura mater; durable; durance; duration; duress; during; durum; endure; hamadryad; indurate; obdurate; perdurable; philodendron; rhododendron; shelter; tar (n.1) "viscous liquid;" tray; tree; trig (adj.) "smart, trim;" trim; troth; trough; trow; truce; true; trust; truth; tryst.
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit dru "tree, wood," daru "wood, log, timber;" Greek drys "oak," drymos "copse, thicket," doru "beam, shaft of a spear;" Old Church Slavonic drievo "tree, wood," Serbian drvo "tree," drva "wood," Russian drevo "tree, wood," Czech drva, Polish drwa "wood;" Lithuanian drūtas "firm," derva "pine, wood;" Welsh drud, Old Irish dron "strong," Welsh derw "true," Old Irish derb "sure," Old Irish daur, Welsh derwen "oak;" Albanian drusk "oak;" Old English treo, treow "tree," triewe "faithful, trustworthy, honest."