‖n. [ NL. See Aëro-; Taxis. ] (Bacteriology) The positive or negative stimulus exerted by oxygen on aërobic and anaërobic bacteria. -- A`ër*o*tac"tic a. [Webster 1913 Suppl.]

n. sn>1. [ Gr. 'ana` back, way from + fy`laxis security, protection. ] 1. (Med.) Hypersensitivity (to a foreign antigen) resulting from prior contact with the same or a related substance. [ WordNet 1.5 + AS ]

2. (Med.) An immediate but transient systemic reaction to an antigenic substance to which a person has become hypersensitized; it is characterized by the contraction of smooth muscle and capillary dilation. [ Stedman ] [ PJC + AS ]

The cascade of events is triggered by binding of the foreign antigen to immunoglobulin E and release of mediators such as histamine, bradykinin, serotonin, and slow-reacting substance from mast cells. It involves more than one organ system. The most commonly involved organs are skin, cardiovascular, respiratory and gastrointestinal systems. Anaphylaxis is manifested by a range of signs and symptoms including pruritus, urticaria, itching, dyspnea, abdominal pain and cardiovascular collapse (shock). A severe form of the reaction is called anaphylactic shock. [ Stedman ] [ PJC + AS ]

3. (Med) Anaphylactic shock. [ AS ]

‖n. [ L. ] (Zool.) The spotted deer (Cervus axis or Axis maculata) of India, where it is called hog deer and parrah (Moorish name). [ 1913 Webster ]

n.; pl. Axes [ L. axis axis, axle. See Axle. ] A straight line, real or imaginary, passing through a body, on which it revolves, or may be supposed to revolve; a line passing through a body or system around which the parts are symmetrically arranged. [ 1913 Webster ]

2. (Math.) A straight line with respect to which the different parts of a magnitude are symmetrically arranged; as, the axis of a cylinder, i. e., the axis of a cone, that is, the straight line joining the vertex and the center of the base; the axis of a circle, any straight line passing through the center. [ 1913 Webster ]

3. (Bot.) The stem; the central part, or longitudinal support, on which organs or parts are arranged; the central line of any body. Gray. [ 1913 Webster ]

4. (Anat.) (a) The second vertebra of the neck, or vertebra dentata. (b) Also used of the body only of the vertebra, which is prolonged anteriorly within the foramen of the first vertebra or atlas, so as to form the odontoid process or peg which serves as a pivot for the atlas and head to turn upon. [ 1913 Webster ]

5. (Crystallog.) One of several imaginary lines, assumed in describing the position of the planes by which a crystal is bounded. [ 1913 Webster ]

6. (Fine Arts) The primary or secondary central line of any design. [ 1913 Webster ]

Anticlinal axis (Geol.), a line or ridge from which the strata slope downward on the two opposite sides. --
Synclinal axis, a line from which the strata slope upward in opposite directions, so as to form a valley. --
Axis cylinder (Anat.), the neuraxis or essential, central substance of a nerve fiber; -- called also axis band, axial fiber, and cylinder axis. --
Axis in peritrochio, the wheel and axle, one of the mechanical powers. --
Axis of a curve (Geom.), a straight line which bisects a system of parallel chords of a curve; called a principal axis, when cutting them at right angles, in which case it divides the curve into two symmetrical portions, as in the parabola, which has one such axis, the ellipse, which has two, or the circle, which has an infinite number. The two axes of the ellipse are the major axis and the minor axis, and the two axes of the hyperbola are the transverse axis and the conjugate axis. --
Axis of a lens, the straight line passing through its center and perpendicular to its surfaces. --
Axis of a microscope or
Axis of a telescope, the straight line with which coincide the axes of the several lenses which compose it. --
Axes of coördinates in a plane, two straight lines intersecting each other, to which points are referred for the purpose of determining their relative position: they are either rectangular or oblique. --
Axes of coördinates in space, the three straight lines in which the coördinate planes intersect each other. --
Axis of a balance, that line about which it turns. --
Axis of oscillation, of a pendulum, a right line passing through the center about which it vibrates, and perpendicular to the plane of vibration. --
Axis of polarization, the central line around which the prismatic rings or curves are arranged. Brewster. --
Axis of revolution (Descriptive Geom.), a straight line about which some line or plane is revolved, so that the several points of the line or plane shall describe circles with their centers in the fixed line, and their planes perpendicular to it, the line describing a surface of revolution, and the plane a solid of revolution. --
Axis of symmetry (Geom.), any line in a plane figure which divides the figure into two such parts that one part, when folded over along the axis, shall coincide with the other part. --
Axis of the
equator, ecliptic, horizon (or other circle considered with reference to the sphere on which it lies), the diameter of the sphere which is perpendicular to the plane of the circle. Hutton. --
Axis of the Ionic capital (Arch.), a line passing perpendicularly through the middle of the eye of the volute. --
Neutral axis (Mech.), the line of demarcation between the horizontal elastic forces of tension and compression, exerted by the fibers in any cross section of a girder. --
Optic axis of a crystal, the direction in which a ray of transmitted light suffers no double refraction. All crystals, not of the isometric system, are either uniaxial or biaxial. --
Optic axis,
Visual axis (Opt.), the straight line passing through the center of the pupil, and perpendicular to the surface of the eye. --
Radical axis of two circles (Geom.), the straight line perpendicular to the line joining their centers and such that the tangents from any point of it to the two circles shall be equal to each other. --
Spiral axis (Arch.), the axis of a twisted column drawn spirally in order to trace the circumvolutions without. --
Axis of abscissas and
Axis of ordinates. See Abscissa. [ 1913 Webster ]

{ n. Formerly also }. [ Chemical + Gr. &unr_; arrangement, fr. &unr_; to arrange. ] (Biol.) The sensitiveness exhibited by small free-swimming organisms, as bacteria, zoospores of algæ, etc., to chemical substances held in solution. They may be attracted (positive chemotaxis) or repelled (negative chemotaxis). -- Chem`o*tac"tic a. -- Chem`o*tac"tic*al*ly, adv. [ Webster 1913 Suppl. ]

n. (Biology) The movement of cells toward or away from other cells, as a result of some stimulation, such as chemical signals transmitted and received by the cells. [ PJC ]

‖n. [ NL., fr. Gr. 'epi` upon + &unr_; to drop. ] (Med.) Bleeding at the nose. [ 1913 Webster ]

‖n. [ NL., fr. Gr. &unr_; the same + &unr_; arrangement. ] (Biol.) Similarly in arrangement of parts; -- the opposite of heterotaxy. [ 1913 Webster ]

n.; pl. Interaxes (Arch.) The space between two axes. See Axis, 6. [ 1913 Webster ]

The doors, windows, niches, and the like, are then placed centrally in the interaxes. Gwilt. [ 1913 Webster ]

n. (Geom.), The greater axis of a geometrical figure. Especially: the longest axis of an ellipse or ellipsoid, which passes through the two foci. See Focus, n., 2. [ WordNet 1.5 +PJC ]

prop. n. A large genus of largely terrestrial orchids with one or a few plicate leaves and slender spikes or tiny mostly green flowers; it is cosmopolitan.
Syn. -- genus Malaxis. [ WordNet 1.5 ]

n. A North American orchid having a solitary leaf and flowers with threadlike petals.
Syn. -- green adder's mouth, Malaxis ophioglossoides. [ WordNet 1.5 ]

n. [ Neuro- + axis. ] (Anat.) See Axis cylinder, under Axis. [ 1913 Webster ]

‖n. [ L., fr. Gr. &unr_;, from &unr_; to assemble illegally or secretly. ] (Civil Law) An unlawful meeting. [ 1913 Webster ]

‖n. [ NL., fr. Gr. &unr_; a placing beside, fr. &unr_; to place beside. ] (Gram.) The mere ranging of propositions one after another, without indicating their connection or interdependence; -- opposed to syntax. Brande & C. [ 1913 Webster ]

{ ‖, n. [ NL. phototaxis; photo- + Gr. &unr_; an arranging. ] (Biol.) The influence of light on the movements of low organisms, as various infusorians, the zoospores of certain algæ, etc.; also, the tendency to follow definite directions of motion or assume definite positions under such influence. If the migration is toward the source of light, it is termed
positive phototaxis; if away from the light,
negative phototaxis. -- Pho`to*tac"tic a. -- Pho`to*tac"tic*al*ly, adv. [ Webster 1913 Suppl. ]

{ } n. [ Phyllo- + Gr. ta`xis order. ] (Bot.) The order or arrangement of leaves on the stem; the science of the relative position of leaves. [ 1913 Webster ]

n. [ NL., fr. Gr. &unr_;, fr. &unr_; to do. See Practice. ] 1. Use; practice; especially, exercise or discipline for a specific purpose or object. “The praxis and theory of music.” Wood. [ 1913 Webster ]

2. An example or form of exercise, or a collection of such examples, for practice. [ 1913 Webster ]

‖n. [ NL. See Prophylactic. ] (Med.) The art of preserving from, or of preventing, disease; the observance of the rules necessary for the preservation of health; preservative or preventive treatment. [ 1913 Webster ]

‖n. [ NL., fr. Gr. &unr_;&unr_;&unr_; a root + &unr_;&unr_;&unr_; arrangement. ] (Bot.) The arrangement of the roots of plants. [ 1913 Webster ]

n. (Geom.) One half of the axis of an &unr_;llipse or other figure. [ 1913 Webster ]

n. [ L., fr. Gr. &unr_;, fr. &unr_; to bring together. See Synagogue. ] A congregation; also, formerly, the Lord's Supper. Jer. Taylor. [ 1913 Webster ]

‖n. Syntax. [ R. ] B. Jonson. [ 1913 Webster ]

‖n. [ NL., fr. Gr. ta`xis a division or arrangement, fr. ta`ssein to arrange. ] 1. (Surg.) Manipulation applied to a hernial tumor, or to an intestinal obstruction, for the purpose of reducing it. Dunglison. [ 1913 Webster ]

2. In technical uses, as in architecture, biology, grammar, etc., arrangement; order; ordonnance. [ Webster 1913 Suppl. ]

3. a reflexive movement by a motile organism by which it moves or orients itself in relation to some source of stimulation; as, chemotaxis, the motion toward or away from gradients of certain chemical compounds. [ PJC ]

n. combining form for taxis{ 3 }. [ PJC ]

n. [ NL.; thermo- + Gr. &unr_; an arranging. ] (Physiol.) (a) The property possessed by protoplasm of moving under the influence of heat. (b) Determination of the direction of locomotion by heat. [ Webster 1913 Suppl. ]

‖n. [ NL., fr. Gr. &unr_; touch + &unr_; an arranging. ] (Physiol.) The property possessed by living protoplasm of contracting, and thus moving, when touched by a solid or fluid substance.

☞ When the movement is away from the touching body, it is negative thigmotaxis; when towards it, positive thigmotaxis. [ Webster 1913 Suppl. ]

n. [ Zoo- + Gr. &unr_; a doing, an acting (from &unr_; to do) + -scope. ] An instrument similar to, or the same as, the, the phenakistoscope, by means of which pictures projected upon a screen are made to exhibit the natural movements of animals, and the like. [ 1913 Webster ]