Ob-tēn'e-brā'tion, n.

n. [From Lat. obtenebrare, to make dark, from prefix ob and tenebrare, to darken, from tenebra, darkness.] The act of darkening; a darkening; darkness. [Obs.]

In every megrim or vertigo, there is an obtenebration joined with a semblance of turning round. Bacon.