[sir-oh-strey-tuh
s, -strat-uhs] 
| a cloud of a class characterized by a composition of ice crystals and often by the production of halo phenomena and appearing as a whitish and usually somewhat fibrous veil, often covering the whole sky and sometimes so thin as to be hardly discernible: of high altitude, ab. 20,000–40,000 ft. (6000–12,000 m). |
| cir·ro·stra·tus (sîr'ō-strā'təs, -strāt'əs) n. A high-altitude, thin, hazy cloud, usually covering the sky and often producing a halo effect. |