"act of rivaling, competition, strife or effort to attain an object another is pursuing," 1590s; from rival (n.) + -ry. Shakespeare has rivality ("Antony and Cleopatra"), but meaning "association, partnership, equality in rank," from the secondary sense of the Latin adjective. Jonson has rivalship (1630s); rivaltry (1640s) also was used.
"sums of money," irregular plural of money that emerged mid-19c. in rivalry to earlier moneys (c. 1300).
"effort to equal or excel in qualities or actions that one admires in another or others; imitative rivalry," 1550s, from French émulation (13c.) and directly from Latin aemulationem (nominative aemulatio) "rivalry, emulation, competition," noun of action from past-participle stem of aemulari "to rival, strive to excel," from aemulus "striving, rivaling" (also as a noun, "a rival," fem. aemula), from Proto-Italic *aimo-, from PIE *aim-olo, suffixed form of root *aim- "copy" (from PIE root *aim- "to copy").
c. 1600, "action of seeking or endeavoring to gain what another is endeavoring to gain at the same time," from Late Latin competitionem (nominative competitio) "rivalry," in classical Latin "agreement," noun of action from past participle stem of competere (see compete).
Meaning "a contest for something, a trial of skill as a test of superiority or fitness" is from 1610s. Sense of "rivalry in the marketplace" attested from 1793; that of "entity or entities with which one competes" is from 1961, especially in business.
1530s, "one who competes in rivalry (with another), a rival," from French compétiteur (16c.), or directly from Latin competitor "rival," agent noun from past-participle stem of competere (see compete). As "one placed in a competition," 1650s.
mid-15c., "engage in rivalry, compete," from Old French contendre and directly from Latin contendere "to stretch out; to shoot, hurl, throw; strive after mentally; measure or try one's strength with, fight, vie with," from assimilated form of com-, here perhaps an intensive prefix (see com-), + tendere "to stretch" (from PIE root *ten- "to stretch"). From 1540s as "to assert, affirm, maintain." Related: Contended; contending.