Quick Definition
ὕαλος, ου, ἡ n.m. glass
Strong's Definition
perhaps from the same as 5205 (as being transparent like rain); glass
KJV Usage: glass
UBS Dictionary of the Greek New Testament
noun, m. | -ου | ὑάλινος
6.222 · Artifacts · Miscellaneous
glass a very hard, translucent, and usually transparent type of quartz It is also possible that ὕαλος should be interpreted as crystal; see 2.46). In REV 21:18 and REV 21:21 the emphasis is upon the transparency of the glass.
2.46 · Natural Substances · Precious and Semiprecious Stones and Substances
crystal a very hard, translucent, and usually transparent type of quartz The equivalent of ‘crystal’ is often a descriptive phrase such as ‘a brilliant stone’ or ‘a shining stone’ or ‘a glass-like stone.’ In developing a satisfactory term for crystal, it is important to avoid possible confusion with diamond.
Some scholars, however, interpret ὕαλος in REV 21:21 as ‘glass’ (see 6.222).
UBS Dictionary of the Greek New Testament © United Bible Societies, licensed CC BY-SA 4.0.
Thayer's Greek Lexicon
ὕαλος, -ov, 6, [prob. allied w. ὕει, ὑετός (q.¥.); hence ‘rain-drop’, Curtius § 604; Wanitek p. 1046; but al. make it of Egypt. origin (cf. L. and 8. 5. v.)], fr. Hat. ([3. 24] who writes ὕελος ; [ef. W. 22]) down; ale any stone transparent like glass. 2. glass: Rev. xxi. 18, 21.
Mounce Concise Greek Dictionary
ὕαλος hyalos 2x
a transparent stone, crystal; also, glass, Rev. 21:18, 21*
Abbott-Smith Greek Lexicon
ὕαλος, -ου, ὁ
[in LXX: Jb 28:17 (זְכוּכִית) * ;]
(Hdt.) a clear transparent stone.
(from Plat. on) glass: Re 21:18, 21.†
Liddell-Scott-Jones — Greek-English Lexicon
ὕαλος (hualos) — glass. ὕᾰλος or ὕελος (see. below), ἡ, see [Refs 4th c.BC+], ὁ:—the form ὕαλος is said to be Attic dialect, ὕελος Hellenic, [Refs 5th c.BC+] and ὕαλο; ὕελος is read in [NT+4th c.BC+]; compare ὑάλινος:—originally some kind of crystalline stone, such as that used by the Ethiopians to enclose their mummies in, [Refs 5th c.BC+]rock-crystal, [Refs 3rd c.AD+]
2. a convex lens of crystal, used as a burning-glass, λίθος διαφανὴς ἀφ᾽ ἧς τὸ πῦρ ἅπτουσι [Refs 5th c.BC+]
II. glass, first in [Refs 5th c.BC+]glass-ware, [Refs 4th c.AD+]
III. ὕαλος χνοώδης, in [Refs 7th c.AD+], is an absorbent of some kind:—ὕαλος is also explained by βόρβορος in [Refs 5th c.AD+]. [ῠᾰλος, as appears from [Refs 5th c.BC+]:—but late Poets make ῡ in some derivations to bring them into dactylic verses, ῡάλεος [Refs]; ῡέλινος [Refs]; ῡαλόεις [Refs]; ῡαλοειδής [Refs 5th c.AD+]; in iambic metre, ῡαλόχροα [Refs]