thumb|individual left and right footprints are chiral enantiomorphs in a plane because they are mirror images while containing no mirror symmetry individually. in geometry, a figure is chiral (and said to have chirality) if it is not identical to its mirror image, or, more precisely, if it cannot be mapped to its mirror image by rotations and translations alone. a chiral object and its mirror image are said to be enantiomorphs. the word chirality is derived from the greek  (cheir), the hand, the most familiar chiral object; the word enantiomorph stems from the greek  (enantios) 'opposite' +  (morphe) 'form'. a non-chiral figure is called achiral or amphichiral. == examples==  {| class=wikitable align=right |+ the tetrominos s and z are enantiomorphs in 2-dimensions !100pxs !100pxz |} some chiral three-dimensional objects, such as the helix, can be assigned a right or left handedness, according to the right-hand rule. many other familiar objects exhibit the same chiral symmetry of the human body, such as gloves and shoes. a right shoe is different from a left shoe only for being mirror images of each other. in contrast thin gloves may not be considered chiral if you can wear them inside-out. the j, l, s and z-shaped tetrominoes of the popular video game tetris also exhibit chirality, but only in a two-dimensional space. individually they contain no mirror symmetry in the plane. ==chirality and symmetry group== a figure is achiral if and only if its symmetry group contains at least one orientation-reversing isometry. (in euclidean geometry any isometry can be written as v\mapsto av+b with an orthogonal matrix a and a vector b. the determinant of a is either 1 or &minus;1 then. if it is &minus;1 the isometry is orientation-reversing, otherwise it is orientation-preserving.) ==chirality in three dimensions==  in three dimensions, every figure which possesses a plane of symmetry or a center of symmetry is achiral. (a plane of symmetry of a figure f is a plane p, such that f is invariant under the mapping (x,y,z)\mapsto(x,y,-z), when p is chosen to be the x-y-plane of the coordinate system. a center of symmetry of a figure f is a point c, such that f is invariant under the mapping (x,y,z)\mapsto(-x,-y,-z), when c is chosen to be the origin of the coordinate system.) note, however, that there are achiral figures lacking both plane and center of symmetry. an example is the figur
Chirality Knot_theory Polyhedra