vault (n.1)
"arched roof or ceiling," c.1300, vaute, from Old French voute "arch, vaulting, vaulted roof or chamber," from Vulgar Latin *volta, contraction of *volvita, noun use of fem. of *volvitus, alteration of Latin volutus "bowed, arched," past participle of volvere "to turn, turn around, roll" (see volvox). The -l- appeared in English c.1400, an etymological insertion in imitation of earlier forms (compare fault (n.)).
vault (v.1)
"jump or leap over," especially by aid of the hands or a pole, 1530s, transitive (implied in vaulting); 1560s, intransitive, from Middle French volter "to gambol, leap," from Italian voltare "to turn," from Vulgar Latin *volvitare "to turn, leap," frequentative of Latin volvere "to turn, turn around, roll" (see volvox). Related: Vaulted; vaulting.
vault (n.2)
"a leap," especially using the hands or a pole, 1570s, from vault (v.1).
vault (v.2)
"to form with a vault or arched roof," late 14c., from Old French vaulter, volter, from voute "arch, vaulted roof" (see vault (n.1)). Related: Vaulted; vaulting.