• WordNet 3.6
    • adj univalve used of mollusks, especially gastropods, as snails etc.
    • n univalve a class of mollusks typically having a one-piece coiled shell and flattened muscular foot with a head bearing stalked eyes
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Webster's Revised Unabridged Dictionary
    • n Univalve (Zoöl) A shell consisting of one valve only; a mollusk whose shell is composed of a single piece, as the snails and conchs.☞ Most univalves are spiral and are the shells of gastropods, but many belong to cephalopods and pteropods. A large number of univalves belonging to the gastropods are conical, cup-shaped, or shieldlike, as the limpets.
    • a Univalve (Bot. & Zoöl) Having one valve; as, a univalve shell or pericarp.
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Century Dictionary and Cyclopedia
    • univalve Having one valve only, as a mollusk; not bivalve or multivalve; univalved or univalvular. See II.
    • univalve Having the carapace single, or not hinged in the middle line: specifying the cladocerous or daphniaceous crustaceans. [Now rare.] In botany, consisting of one valve or piece.
    • n univalve In conchology, a univalve mollusk or its shell; a shell consisting of a single piece; formerly, a member of one of three Linnean divisions of Testacea, as distinguished from bivalves and multivalves. The great group of gastropods are univalves. The single valve is sometimes very small, slight, rudimentary, or hidden beneath the mantle; but in most cases it is large and stout, nearly or completely inclosing the soft parts; and in such cases it usually acquires a twist or spiral coil, either in one plane, or, oftener, rising in a conical spire endlessly varied in details of size, shape, etc. Such coiled univalve shells are familiar objects, as those of the snail, whelk, periwinkle, etc. Sometimes the coils are quite fiat, as in the planorbis; or the spire is so slight, and the first whorl so large, that the resulting figure is ear-like or saucer-shaped, as in the ormer. Some univalves are simple caps or cones, as the limpets. Some are tubular, as the tooth-shells; or tubular and variously contorted, as the worm-shells or vermetids. Some have an egg-shaped or fusiform figure. Many univalves have actually a second shell or valve, the operculum or lid of the aperture; this, however, does not count against their being univalvular. Many forms of ordinary univalves have special names, as helicoid, conoid, discoid, ovoid, trochoid, turbinate, turreted. The direction or the coiling, whether right or left, is dextrorse or sinistrorse; a coiling in the opposite from the usual direction is reversed. The first whorl of a spiral univalve is the body-whorl; its opening is the aperture; the lips of the aperture are the outer or labrum, and the inner or columellar, the labium; the lips may be variously produced, winged or alate, canaliculate, etc. (See holostomatous, siphonostomatous.) The central pillar around which the whorls are coiled is the columella; the whorls above the
    • n univalve body-whorl or aperture are collectively the spire, ending at the tip, point, or apex. The opposite end of the shell is the base, which often presents a depression, the umbilicus; the circumference, a completely lipped aperture, is the peristome. The spiral line between the successive whorls or volutions is the suture. See words italicized above with various cuts there, or there cited.
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Chambers's Twentieth Century Dictionary
    • adj Univalve ū′ni-valv having one valve or shell only
    • n Univalve a shell of one valve only: a mollusc whose shell is composed of a single piece
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Webster's Revised Unabridged Dictionary
Uni-, + valve,: cf. F. univalve,


In literature:

There are three varieties, spiral, univalve, and bivalve.
"Missionary Travels and Researches in South Africa" by David Livingstone
Group of Upper Silurian Univalves.
"The Ancient Life History of the Earth" by Henry Alleyne Nicholson
The objects are generally made from large pear-shaped sections of the lower whorl of marine univalves.
"Illustrated Catalogue of a Portion of the Collections Made" by William H. Holmes
Cochleate: spirally twisted like a screw or a univalve shell.
"Explanation of Terms Used in Entomology" by John. B. Smith
The mother-of-pearl which lines some shells, both univalve and bivalve.
"The Sailor's Word-Book" by William Henry Smyth
The Japanese tops are of several kinds, some are made of univalve shells, filled with wax.
"Child-Life in Japan and Japanese Child Stories" by Mrs. M. Chaplin Ayrton
Caracol, a conch, a univalve shell.
"The Arawack Language of Guiana in its Linguistic and Ethnological Relations" by Daniel G. Brinton
The eggs of the univalve Mollusca are hardly less varied in the shapes they take.
"Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 1" by Various
But a great number of the bivalve Testacea, and many also of the turbinated univalves, burrow in sand or mud.
"Principles of Geology" by Charles Lyell
On the other hand, Volutes and other genera of univalve shells, usually met with only in tertiary strata, occur.
"A Manual of Elementary Geology" by Charles Lyell