Word Origin & History
rare (adj.1)
"unusual," c.1420, originally "few in number and widely separated," from O.Fr. rere "sparse" (14c.), from L. rarus "thinly sown, having a loose texture," from PIE *er-, *ere- "to loose, split, separate" (cf. Skt. rte "besides, except," viralah "distant, tight, rare;" O.C.S. oriti "to dissolve, destroy;" Lith. irti "to dissolve;" O.C.S. rediku "rare;" Gk. eremos "solitary"). "Few in number," hence, "unusual" (1542). Rarity is attested from 1560, from M.Fr. rarité (16c.), from L. raritas "thinness, fewness," from rarus. In chemistry, rare earth is from 1875.