"having the quality of duplicating or doubling," 1854; see duplicate (v.) + -ive.

"deceptive, acting or speaking differently of the same thing at different times or to different persons," 1831; see duplicity + -ous.

"deceptiveness, character or practice of speaking differently of the same thing or acting differently at different times or to different persons," early 15c., from Old French duplicite (13c.), from Late Latin duplicitatem (nominative duplicitas) "doubleness," in Medieval Latin "ambiguity," noun of quality from duplex (genitive duplicis) "twofold," from duo "two" (from PIE root *dwo- "two") + -plex, from PIE root *plek- "to plait." The notion is "a state of being double" in one's conduct (compare Greek diploos "treacherous, double-minded," literally "twofold, double").

"tough outer membrane surrounding the brain and the spinal cord," c. 1400, from Medieval Latin dura mater cerebri, literally "hard mother of the brain," a loan-translation of Arabic umm al-dimagh as-safiqa, literally "thick mother of the brain." "In Arabic, the words 'father,' 'mother,' and 'son' are often used to denote relationships between things" [Klein].

"power of lasting or continuing in the same state, resistance to decay or dissolution," late 14c., from Old French durabilité and directly from Late Latin durabilitatem (nominative durabilitas), noun of quality from Latin durabilis "lasting, permanent," from durare "to harden," from durus "hard," from PIE *dru-ro-, suffixed variant form of root *deru- "be firm, solid, steadfast."

late 14c., "having the quality of continuing long in being," from Old French durable (11c.) and directly from Latin durabilis "lasting, permanent," from durare "to harden," from durus "hard," from PIE *dru-ro-, suffixed variant form of root *deru- "be firm, solid, steadfast." From late 13c. as a surname (probably meaning "steadfast"). Related: Durably. Durable goods attested from 1930.

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."

"continuance in time; length of time during which anything continues," late 14c., duracioun, from Old French duration, from Medieval Latin durationem (nominative duratio), noun of action from past-participle stem of Latin durare "to harden," from durus "hard," from PIE *dru-ro-, suffixed variant form of root *deru- "be firm, solid, steadfast." The old legalese phrase for the duration was popularized 1916 in reference to British enlistments in World War I.

early 14c., "harsh or severe treatment," from Old French duresse, durece, from Latin duritia "hardness," from durus "hard," from PIE *dru-ro-, suffixed variant form of root *deru- "be firm, solid, steadfast." For Old French -esse, compare fortress. Sense of "coercion, compulsion" is from early 15c.; in law, "actual or apprehended physical constraint so great as to amount to coercion" (early 15c.).

c. 1000, Dunholm "city on a hill," a merger of Old English dun "hill" (see down (n.2)) and Scandinavian holmr (see holm). The change from -n- to -r- is a result of Norman confusion (see Shrewsbury). As a breed of short-horned cattle, by 1810, so called from being bred there.