Here’s a super interesting series of definitions from the Online Etymology Dictionary.
late 14c., “to undergo or suffer” (especially without breaking); also “to continue in existence,” from Old French endurer (12c.) “make hard, harden; bear, tolerate; keep up, maintain,” from Latin indurare “make hard,” in Late Latin “harden (the heart) against,” from in- (from PIE root *en “in”) + durare “to harden,” from durus “hard,” from PIE *dru-ro-, suffixed variant form of root *deru- “be firm, solid, steadfast.”
Replaced the important Old English verb dreogan (past tense dreag, past participle drogen), which survives in dialectal dree. Related: Endured; endures.
“lasting,” 1530s, present-participle adjective from endure.
late 15c., “continued existence in time;” see endure + -ance. Meaning “ability to bear suffering, etc.” is from 1660s.
c. 1600, “able to endure,” from endure + -able, or from French endurable. Meaning “able to be endured” is from 1744. Related: Endurably.
Proto-Indo-European root meaning “in.”
It forms all or part of: and; atoll; dysentery; embargo; embarrass; embryo; empire; employ; en- (1) “in; into;” en- (2) “near, at, in, on, within;” enclave; endo-; enema; engine; enoptomancy; enter; enteric; enteritis; entero-; entice; ento-; entrails; envoy; envy; episode; esoteric; imbroglio; immolate; immure; impede; impend; impetus; important; impostor; impresario; impromptu; in; in- (2) “into, in, on, upon;” inchoate; incite; increase; inculcate; incumbent; industry; indigence; inflict; ingenuous; ingest; inly; inmost; inn; innate; inner; innuendo; inoculate; insignia; instant; intaglio; inter-; interim; interior; intern; internal; intestine; intimate (adj.) “closely acquainted, very familiar;” intra-; intricate; intrinsic; intro-; introduce; introduction; introit; introspect; invert; mesentery.
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit antara- “interior;” Greek en “in,” eis “into,” endon “within;” Latin in “in, into,” intro “inward,” intra “inside, within;” Old Irish in, Welsh yn, Old Church Slavonic on-, Old English in “in, into,” inne “within, inside.”
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 drutas “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.”
Old English dreogan “to work, suffer, endure;” see drudge. Cognate of Old Norse drygjado “carry out, accomplish,” Gothic driugan “serve as a soldier.”
word-forming element attached to verbs to form abstract nouns of process or fact (convergence from converge), or of state or quality (absence from absent); ultimately from Latin -antia and -entia, which depended on the vowel in the stem word, from PIE *-nt-, adjectival suffix.
As Old French evolved from Latin, these were leveled to -ance, but later French borrowings from Latin (some of them subsequently passed to English) used the appropriate Latin form of the ending, as did words borrowed by English directly from Latin (diligence, absence).
English thus inherited a confused mass of words from French and further confused it since c. 1500 by restoring -ence selectively in some forms of these words to conform with Latin. Thus dependant, but independence, etc.