An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

Same as → optical depth.

→ optical; → thickness.

The state or quality of being thick. → optical thickness.

M.E. thiknesse, O.E. thicnes, from → thick + -nes(s) suffix of action, quality or state, cf. M.Du. -nisse, O.H.G. -nissa, Ger. -nis, Goth. -inassus.

Setabrâ, from setabr→ thick + -â a suffix forming nouns from adjectives.