Emily Dickinson Lexicon

NEB'U-LA, or NEB'ULE, n. [L. nebula; Gr. νεφος, νεφελη; G. nebel; D. nevel; Ir. neall, neul, by contraction; It. nebbia; Sp. niebla, fog, mist; Sans. nabha, a cloud. Probably the primary sense is thick or mixed.]

1. A white spot, or a slight opacity of the cornea. Cyc.
2. In astronomy, a cluster of fixed stars, not distinguishable from each other or scarcely visible to the naked eye, and exhibiting a dim hazy light, appearing like dusky specks or clouds through the telescope. Cyc.
3. [In heraldry, it is used, to describe a line drawn with undulations resembling the form of clouds; or a shield or trunk charge divided by several such lines drawn across it. E. H. B.]