The Collaborative International Dictionary of English v.0.48:

Caligation \Cal`i*ga"tion\ (-g[=a]"sh[u^]n), n. [L. caligatio,
   fr. caligare to emit vapor, to be dark, from caligo mist,
   darkness.]
   Dimness; cloudiness. [R.] --Sir T. Browne.
   [1913 Webster]