O*pa"cous (?), a. [L. opacus. See Opaque.] Opaque. [R.] Milton. --
O*pa"cous*ness, n. [R.]
O*pac"u*lar (?), a. Opaque. [Obs.] Sterne.
O"pah (?), n. (Zoöl.) A large oceanic fish (Lampris quttatus),
inhabiting the Atlantic Ocean. It is remarkable for its brilliant
colors, which are red, green, and blue, with tints of purple and gold,
covered with round silvery spots. Called also king of the herrings.
O*pake" (?), a. See Opaque.
O"pal (?), n. [L. opalus: cf. Gr. &?;, Skr. upala a rock, stone,
precious stone: cf. F. opale.] (Min.) A mineral consisting, like
quartz, of silica, but inferior to quartz in hardness and specific
gravity.
The precious opal presents a peculiar play of colors of delicate tints,
and is highly esteemed as a gem. One kind, with a varied play of color
in a reddish ground, is called the harlequin opal. The fire opal has
colors like the red and yellow of flame. Common opal has a milky
appearance. Menilite is a brown impure variety, occurring in
concretions at Menilmontant, near Paris. Other varieties are cacholong,
girasol, hyalite, and geyserite.
O`pal*esce" (?), v. i. [imp. & p. p. Opalesced (?); p. pr. & vb. n.
Opalescing (?).] To give forth a play of colors, like the opal.
O`pal*es"cence (?), n. (Min.) A reflection of a milky or pearly light
from the interior of a mineral, as in the moonstone; the state or
quality of being opalescent.
O`pal*es"cent (?), a. Reflecting a milky or pearly light from the
interior; having an opaline play of colors.
O"pal*ine (?), a. [Cf. F. opalin.] Of, pertaining to, or like, opal in
appearance; having changeable colors like those of the opal.
O"pal*ize (?), v. t. [imp. & p. p. Opalized (?); p. pr. & vb. n.
Opalizing.] [Cf. F. opaliser.] To convert into opal, or a substance
like opal. Lyell.
O*pal"o*type (?), n. [Opal + -type.] (Photog.) A picture taken on
"milky" glass.