1) One of the principal lines through the center of a figure or a
solid, especially, the line which divides the figure or solid
L. axis "axle, pivot," akin to O.E. eax "axis, axle," Gk. axon "axle," Skt. aksa- "axle, axis, beam of a balance;" PIE base *aks- "axis."
Âsé, from Pers. dialects: Qâyeni asak "the shaft connecting the plough to the yoke," Lori esi "a pillar (used to put up a tribal tent)," variants hosi, hosin, Tabari âssen "the foot of a door on which it turns," cf. Skt. ISA- "pole or shafts of a carriage or plough," Av. aêša "the two shafts," Mod.Pers. xiš "plough(share)," Gk. oiax "handle of rudder, tiller, helm," PIE base *ei-, *oi- "pole, thill."
axis of rotation
Fr.: axe de rotation
hamâmun-e âse-yi, âse-hamâmun
Having → axisymmetry.
hamâmuni-ye âse-yi, âse-hamâmuni
Same as → axial symmetry.
âse-ye âsmân (#)
Fr.: axe du monde
The Earth's axis extended to the → celestial pole.
Fr.: axe conjugué
One of the two diameters of a conic, so related that a tangent at the end of one is parallel to the other.
Fr.: axe de déclinaison
The axis to which the telescope tube is fastened in an → equatorial mounting.
inclination of axis
Fr.: inclinaison de l'axe
The angle between the rotation axis of a planet and the normal to the ecliptic.
Fr.: axe magnétique
Fr.: grand axe
The greatest diameter of an ellipse; it passes through the two foci.
Fr.: petit axe
The axis of an ellipse that is perpendicular to the major axis at a point equidistant from the foci.
off-axis optical system
râžmân-e nurik-e ap-âsé
Fr.: système optique hors axe
Fr.: axe optique
The direction in a doubly refracting crystal in which light is propagated without double refraction.
âse-ye nuri (#)
Fr.: axe optique
Fr.: axe orbital
parallel axis theorem
farbin-e âsehâ-ye parâsu
Fr.: théorème des axes parallèles
The → moment of inertia of a body about any given axis is the moment of inertia about a parallel axis through the center of mass, plus the moment of inertia about the given axis if the mass were located at the center of mass. same as → Steiner's theorem.
perpendicular axis theorem
farbin-e âsehâ-ye pâlâr
Fr.: théorème des axes perpendiculaires
The → moment of inertia of a plane object (→ lamina) about an axis perpendicular to the plane is equal to the sum of the moments of inertia about any two perpendicular axes in the plane. Thus if x and y axes are in the plane, Iz = Ix + Iy.
âse-ye qotbi (#)
Fr.: axe polaire
The axis of an → equatorial mounting that is parallel to the Earth's axis, and consequently points to the celestial pole.
1) The practice and practical side of knowledge or skills, as opposed to the
M.L. praxis "practice, action," from Gk. praxis "practice, action, doing," from stem of prassein "to do, to act."
Varzidâr, from varzid past stem of varzidan, → practice, + -âr prefix forming nouns of action, such as kerdâr, raftâr, didâr, goftâr, jostâr, etc.
âse-ye farin (#)
Fr.: axe principal
Any imaginary line passing through the center of curvature of a
→ spherical mirror
or → lens and the corresponding geometrical center.
Principal axis is perpendicular
to the mirror or lens at the pole.
Rays of light parallel to the principal axis of a
→ concave mirror
will appear to converge on a point in front of the mirror somewhere
between the mirror's pole and its center of curvature.
Same as → optical axis.