• WordNet 3.6
    • adj concave curving inward
    • ***
Webster's Revised Unabridged Dictionary
    • Concave (Mech) A curved sheath or breasting for a revolving cylinder or roll.
    • Concave A hollow; an arched vault; a cavity; a recess. "Up to the fiery concave towering hight."
    • Concave Hollow and curved or rounded; vaulted; -- said of the interior of a curved surface or line, as of the curve of the of the inner surface of an eggshell, in opposition to convex; as, a concave mirror; the concave arch of the sky.
    • Concave Hollow; void of contents. "As concave . . . as a worm-eaten nut."
    • v. t Concave To make hollow or concave.
    • ***
Century Dictionary and Cyclopedia
    • concave Curved or rounded in the manner of the circumference of a circle or the surface of a sphere when viewed from the center; presenting a hollow or incurvation; incurved; hence, bounded by such a line or surface: as, a concave mirror. A concave bounding surface of a body is one which is so bent that a straight line joining any two points of it lies without the body. Thus, if a ball floats upon water, the common surface of the ball and water is concave if conceived as belonging to the water, and convex if conceived as belonging to the ball. A surface or curve is said to be concave toward the region which would be outside a body of which the curve or surface was a concave boundary.
    • concave Hollow; empty.
    • n concave A hollow; an arch or vault; a concavity.
    • n concave Any inwardly curved portion of a machine: as, the concave of a thresher (the curved breast in which the cylinder works).
    • n concave A concave mirror.
    • concave To make hollow.
    • n concave The vault or arch of heaven: as, “the blue concave.”
    • n concave A playing card so trimmed that it can be separated from others according to the purpose for which the pack was prepared.
    • ***
Chambers's Twentieth Century Dictionary
    • adj Concave kon′kāv curved, vaulted, or arched, applied to the inner side of any curved line or rounded body, and opposed to convex, which is applied to the outside
    • n Concave a hollow: an arch or vault
    • ***


Webster's Revised Unabridged Dictionary
L. concavus,; con-, + cavus, hollow: cf. F. concave,. See Cave a hollow


In literature:

Save for its mud walls, its concave, dome-roof, it might have been a cookery of the Highlands.
"Astounding Stories of Super-Science September 1930" by Various
Several were working desperately at a huge concave glass reflector.
"Pirates of the Gorm" by Nat Schachner
His cheek-bones, a trifle high, asserted their place above the softly concave cheeks.
"Dr. Sevier" by George W. Cable
As a rule, two reflectors are fixed in the same holder; one a concave mirror, the other a plane one.
"The Story of the Cotton Plant" by Frederick Wilkinson
The whirring sound continued, and the concave reflector turned with a grating sound on its gears.
"Astounding Stories of Super-Science, March 1930" by Various
Attached to it, and following the mole, is a carrier 200 feet long, made concave in form.
"Prairie Farmer, Vol. 56: No. 4, January 26, 1884" by Various
By the time the five-mile height was reached Earth's surface had changed definitely from concave to convex.
"Astounding Stories of Super-Science, August 1930" by Various
A concave mirror, which is one that is hollowed out toward the middle, does the same thing.
"Common Science" by Carleton W. Washburne
If rays of fire play on a concave mirror when it is cold, the rays refracted by the mirror will be hotter than {156} the fire.
"Thoughts on Art and Life" by Leonardo da Vinci
This was now a small, circular room, under a lowering concave dome.
"Astounding Stories, March, 1931" by Various
Thick cables ran to a bank of concave reflectors of some gleaming grayish metal.
"Astounding Stories of Super-Science January 1931" by Various
Place the concave sides together and tie in the butt ends the same as for a wet fly.
"How to Tie Flies" by E. C. Gregg
It forms a sort of broken crescent, with the concavity towards the west.
"Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 3" by Various
Cans should have a concave appearance on the top.
"Dietetics for Nurses" by Fairfax T. Proudfit
They can no more be separated than the convex and concave aspects of a curve.
"A Critical History of Greek Philosophy" by W. T. Stace
They depend also upon the concave Surface, because without that Surface a Speculum makes them not.
"Opticks" by Isaac Newton
Often white underneath, Smooth, all black on rear concaved and scalloped on margin.
"Whales, Dolphins, and Porpoises of the Western North Atlantic" by Stephen Leatherwood
He adjusted three of the concave mirrors, and switched on another motor.
"Signal in the Dark" by Mildred A. Wirt
Southward of the concave side of this arc no buildings were for a long time permitted to be erected.
"Toronto of Old" by Henry Scadding
The stream was there; and for want of a better vessel, the concave blades of the maguey would have served as a cistern.
"The Headless Horseman" by Mayne Reid

In poetry:

All ether burns: Chaos returns,
And blends, once more, the seas and skies:
No space between Thy bosom green,
O Deep! and the blue concave, lies.
"Ocean: An Ode. Concluding With A Wish." by Edward Young
Ye Mists and Vapours, Hail and Snow,
And you who through the Concave blow,
Swift Executors of his holy Word,
Whirlwinds and Tempest, praise th'Almighty Lord.
"A Paraphrase On The CXLVIIIth Psalm" by Wentworth Dillon
When Evening bids the Sun to rest retire,
Unwearied Ether sets her lamps on fire;
Lit by one torch, each is supplied in turn,
Till all the candles in the concave burn.
"On The Evening And Morning" by George Moses Horton
Must I no more on midnight-splendors gaze,
Nor woo fair Cynthia's sweetly-pensive beam;
Must, O ye stars! your thousand golden rays,
And heaven's blue concave vanish as a dream?
"Time: An Elegy. Written Near The Ruins Of Elgin Cathedral" by Robert Alves
And we, creation's princes, we,
The favourites of the Deity,
The wise—the strong—whose thoughts can soar
Heaven's brightest, highest concave o'er;
And hold, above created things,
Communion with the King of kings—
"Spring: Thursday Morning" by John Bowring
In the liquid vault of ether hung the starry gems of light,
Blazing with unwonted splendor on the ebon brow of night;
Far across the arching concave like a train of silver lay,
Nebulous, and white, and dreamy, heaven's star-wrought Milky Way.
"The Soul’s Destiny" by Effie Afton

In news:

The one-square-inch cutter has a quarter-inch-thick body that encloses a concaved circle, which has another circle at its center.
HOW TO Create Soft Concave Layers by Angelo Pacente.
A racy concave grille with quad lamps snarls at the pavement before it.
Many of today's roller camshafts have a re-entrant (concave) profile in the flank areas.
The Concave Cylindrical 5mm (T1-3/4) Discrete LEDs from LEDtronics®, the manufacturer and designer of LED products such as panel mount LEDs and PCB LEDs, emit light that is as bright at its edges as it is in the center.
China's Chic Waistline: Convex to Concave .
China's Chic Waistline: Convex to Concave.
The A2 employs all new Variable Concave Technology for maximum speed and angle with safety to match.
China's Chic Waistline : Convex to Concave.
With the concave shape of the asphalt lanes, the path of the ball can be unpredictable.
I think the weirdest one was a concave tube that required users to stick their heads inside the enclosure while an image was projected all around.
Photo courtesy of Tewksbury Township police Note the round concave indentation to the left.
The get the full experience, watch this on a giant concave screen.
A Matt Manzari-inspired creation Three-layer sandwich EVA innovation ABS-wrapped bottom deck 3D concave top deck EVA creates rebound and snap.
Virtually everything said and done in a presidential election year distorts the truth, much like concave and convex mirrors in a carnival attraction alter one's true reflection.

In science:

Let y : R+ → R+ be a concave surjection whose inverse y−1 satis fies the D2 -condition.
A generalized mean value inequality for subharmonic functions and applications
It is defined for all positive x, and is an increasing and concave function.
Non-unique way to generalize the Boltzmann-Gibbs distribution
Moreover, the stability conditions, that S is a concave function of U and that U is an increasing function of T , are satisfied.
Non-unique way to generalize the Boltzmann-Gibbs distribution
On the other hand, for simulation A2, the curve through the data is concave downward for ld < r0 < lB .
Thermal conduction and particle transport in strong MHD turbulence, with application to galaxy-cluster plasmas
On the other hand, for simulation A2, the curve through the data is concave downward for ld < r0 < lB .
The divergence of neighboring magnetic field lines and fast-particle diffusion in strong magnetohydrodynamic turbulence, with application to thermal conduction in galaxy clusters
A probability distribution on E is log concave if the log of its Radon-Nikodym derivative f with respect to E is a concave function. (In particular, f is continuous on the interval on which it is finite).
Random Surfaces
Log concavity also implies that f (a)2 ≥ f (a + c)f (a − c) for all c ∈ Z.
Random Surfaces
If φ is a random function chosen from γΛ (·|φ0), then the law of φ(x0 ) is log concave.
Random Surfaces
Lemma 8.2.5 If Φ is a simply attractive measure, and µ ∈ exG(Ω, F), and x ∈ Zd then the density of the height distribution of φ(x), for φ chosen from µ, is log concave.
Random Surfaces
The reader may check that the τ -topology limit of a sequence of log concave distributions on R or Z is necessarily log concave, and the result then follows.
Random Surfaces
The fact that a distribution ν is log concave implies that the log probabilities must decrease at least linearly; thus, the tails of ν decrease exponentially, and moments of all orders exist.
Random Surfaces
Log concavity also yields a simple proof of the existence of an ergodic L-invariant gradient Gibbs measure of a given slope u ∈ UΦ with σ(u) < ∞.
Random Surfaces
Now, using the notation of Section 4.2, Lemma 8.2.4 implies that the probability density of φg (y ) − φg (x) induced by µn is log concave for any x, y ∈ Zd .
Random Surfaces
The mean photon-number distribution smoothly changes from a sharpsquared distribution to a concave curve that is typical of a classical distribution .
Simulation of quantum random walks using interference of classical field
Let a twice differentiable concave functional S be defined in intU , and let S is continuous on U .
Geometry of irreversibility: The film of nonequilibrium states