endurance n.

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.

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.

Latin present-participle endings for verbs stems in -a- were distinguished from those in -i- and -e-. Hence Modern English protestant, opponent, obedient from Latin protestare, opponere, obedire.

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 (crescent/croissant), 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.

mid-15c., "duration, continuance" (a sense now obsolete; probably an abbreviated form of endurance); sense of "imprisonment, restraint of the person, involuntary confinement" is from 1510s, from Old French durance "duration," from durer "to endure," from Latin durare "to harden," from durus "hard," from PIE *dru-ro-, suffixed variant form of root *deru- "be firm, solid, steadfast."