Not convex; having at least one internal angle greater than 180 degrees.
Hollow; empty.
Satisfying the property that all segments connecting two points on the function's graph lie below the function.
Curved like the inner surface of a sphere or bowl.
A playing card made concave for use in cheating.
One of the celestial spheres of the Ptolemaic or geocentric model of the world.
An indentation running along the base of a surfboard, intended to increase lift.
An element of a curved grid used to separate desirable material from tailings or chaff in mining and harvesting.
The vault of the sky.
An indented area on the top of a skateboard, providing a position for foot placement and increasing board strength.
A concave surface or curve.
To render concave, or increase the degree of concavity.
Not crooked or bent; having a constant direction throughout its length.
Direct, undeviating.
Describing the bat as held so as not to incline to either side; on, or near a line running between the two wickets.
Making no exceptions or deviations in one's support of the organization and candidates of a political party.
Occurring between people of opposite sex (sometimes, but not always, specifically between heterosexual people).
Strait; narrow.
Conventional; mainstream; socially acceptable.
Thorough; utter; unqualified.
Of spirits: undiluted, unmixed; neat.
Concerning the property allowing the parallel transport of vectors along a course that keeps tangent vectors remain as such throughout that course (a course which is straight, a straight curve, is a geodesic).
Not plus size; thin.
In proper order; as it should be.
Heterosexual.
Serious rather than comedic.
Containing the names of all the regularly nominated candidates of a single party and no others.
Related to conventional sexual intercourse.
Free from dishonesty; honest, law-abiding.
Perfectly horizontal or vertical; not diagonal or oblique.
In a row, in unbroken sequence; consecutive.
Not using alcohol, drugs, etc.
Describing the sets in a match of which the winner did not lose a single set.
Direct in communication; unevasive, straightforward.
To straighten.
A chiropractor who relies solely on spinal adjustment, with no other treatments.
Something that is not crooked or bent such as a part of a road or track.
Five cards in sequence.
A cigarette, particularly one containing tobacco instead of marijuana.
A heterosexual.
A normal person; someone in mainstream society.
Directly; without pause, delay or detour.
Continuously; without interruption or pause.
Of speech or information, without prevarication or holding back; directly; straightforwardly; plainly.
Of a direction relative to the subject, precisely; as if following a direct line.