c.1400, from O.Fr. obscur "dark, dim, not clear," from L. obscurus "covered over, dark, obscure, indistinct," from ob "over" + -scurus "covered," from PIE *(s)keu- "to cover, conceal;" source of O.N. sky, O.E. sceo "cloud," and L. scutum "shield" and Gk. skeue "dress" (see sky). The verb is first recorded early 15c.