1834, "fact or condition of being relative, existence as an immediate object of the understanding or experience, existence only in relation to a thinking mind," (apparently coined by Coleridge, in "Notes on Waterland's Vindication of Christ's Divinity"), from relative (adj.) + -ity. In scientific use, connected to the theory of Albert Einstein (1879-1955) having to do with the dependence of observation on the relative motion of observer and object, published in 1905 (special theory of relativity) and 1915 (general theory of relativity), but the word was used in roughly this sense by J.C. Maxwell in 1876. An earlier noun in the sense of "state of being relative" was relativeness (1670s).
"extreme poverty, indigence, destitution," c. 1400, penurie, from Latin penuria "want, need; scarcity," related to pæne "nearly, almost, practically," which is of uncertain origin.
1. "person who kills a parent or near relative" (1550s), also 2. "act of killing a parent or near relative" (1560s), both from French parricide (13c. in sense 1, 16c. in sense 2), from 1. Latin parricida, 2. Latin parricidium, probably from parus "relative" (a word of uncertain origin, but compare Greek paos, peos "relation," Sanskrit purushah "man") + 1. cida "killer," 2. cidium "killing," both from caedere "to kill, to cut down" (from PIE root *kae-id- "to strike"). Old English had fæderslaga. Related: Parricidal.
ancient Greek colony in Libya; the name is of unknown origin. Cyrenaic (1640s) typically refers to the philosophy ("practical hedonism") of Aristippus of Cyrene (c. 435-c. 356 B.C.E.); as a noun, "a Cyrenaic philosopher," from 1580s.
According to Aristippus, pleasure is the only rational aim, and the relative values of different pleasures are to be determined by their relative intensities and durations. He maintained also that cognition is limited to sensation. [Century Dictionary]