The Collaborative International Dictionary of English v.0.48:

Opal \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.
   [1913 Webster]

   Note: 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.
         [1913 Webster]

WordNet (r) 3.0 (2006):

opal
    n 1: a translucent mineral consisting of hydrated silica of
         variable color; some varieties are used as gemstones

The Free On-line Dictionary of Computing (30 December 2018):

Opal

   1. A DSP language.

   ["OPAL: A High Level Language and Environment for DSP boards
   on PC", J.P. Schwartz et al, Proc ICASSP-89, 1989].

   2. The language of the object-oriented database GemStone.

   ["Making Smalltalk a Database System", G. Copeland et al, Proc
   SIGMOD'84, ACM 1984, pp.316- 325].

   3. A simulation language with provision for stochastic
   variables.  An extension of Autostat.

   ["C-E-I-R OPAL", D. Pilling, Internal Report,
   C.E.I.R. Ltd. (1963)].

   4. A language for compiler testing said to be used internally
   by DEC.

   5. A functional programming language designed at the
   Technische Universitaet Berlin as a testbed for the
   development of functional programs.  OPAL integrates
   concepts from Algebraic Specification and Functional
   Programming, which favour the (formal) development of (large)
   production-quality software written in a purely functional
   style.

   The core of OPAL is a strongly typed, higher-order,
   strict applicative language which belongs to the tradition
   of Hope and ML.  The algebraic flavour of OPAL is visible
   in the syntactical appearance and in the preference of
   parameterisation to polymorphism.

   OPAL supports: information hiding - each language unit is
   divided into an interface (signature) and an implementation
   part; selective import; parameterised modules; free
   constructor views on sorts, which allow pattern-based
   function definitions despite quite different implementations;
   full overloading of names; puristic scheme language with no
   built-in data types (except Booleans and denotations).

   OPAL and its predecessor OPAL-0 have been used for some time
   at the Technische Universitaet Berlin in CS courses and for
   research into optimising compilers for applicative languages.
   The OPAL compiler itself is writte entirely in OPAL.

   An overview is given in "OPAL: Design And Implementation of an
   Algebraic Programming Language".

   (http://cs.tu-berlin.de/~opal/).


(ftp://ftp.cs.tu-berlin.de/pub/local/uebb/papers/DesignImplOpal.ps.gz).

   (1995-02-16)


U.S. Gazetteer Places (2000):

Opal, WY -- U.S. town in Wyoming
   Population (2000):    102
   Housing Units (2000): 48
   Land area (2000):     0.430749 sq. miles (1.115636 sq. km)
   Water area (2000):    0.000000 sq. miles (0.000000 sq. km)
   Total area (2000):    0.430749 sq. miles (1.115636 sq. km)
   FIPS code:            57810
   Located within:       Wyoming (WY), FIPS 56
   Location:             41.770449 N, 110.325918 W
   ZIP Codes (1990):
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Opal, WY
    Opal