taxi-, tax-, taxo-, taxio-, -taxia, -taxis, -taxy, tact-, -tactic, -tactical, -tactics

(Greek: arrangement, order, put in order, orientation; the movements or directed responses of motile organisms to stimuli, as indicated by the combining roots)

cytotaxis
1. The mutual attraction or repulsion of cells or groups of motile cells.
2. The movement of a cell toward or away from some sort of stimulus.

The stimulus would then be called the cytotaxin.

diaphototaxis, diaphototactic
An orientation response of an organism or structure at right angles to the direction of incident light.
dysgrammataxia
Difficulty in combining into an integrated whole the various symbols comprising a word or phrase.
ecotaxis
The migration of lymphocytes from the thymus and bone marrow into tissues with a suitable microenvironment.
electrotaxis, electrotactic
1. The movement of cells and organisms toward or away from an electrical current stimulus.
2. The movement of cells or organisms in response to electric current.

It can be either negative, when movement is toward the anode, or positive, when movement is toward the cathode.

epitaxis
Oriented overgrowth of a crystaline material on the surface of another with a similar structure, but with a different chemical composition.
eutaxis, eutaxy
1. Good or established order or arrangement.
2. Good order or management; a well-suited structure.
galvanotaxis, galvanotactic
1. Movement of certain organisms in relation to the direction of an electric field or current.
2. A directed reaction of a motile organism to an electric current.
geotactic (noun) (not comparable)
Referring to the movement of a motile organism using the Earth's gravity for orientation: Geotactic locomotion of a life form orients itself by the force of gravity.
geotaxis (s) (noun), geotaxes (pl)
A locomotor movement by an animal in response to a gravitational stimulus: Geotaxis is a directed response of a motile (moving) organism towards (positive) or away from (negative) the direction of gravity-

Geotaxis can be a movement of a motile micro-organism or cell in response to the force of gravity.

glycotaxis
The distribution of sugars in the body by metabolic processes.
heliotaxis, heliotactic
1. The movement of an organism in response to sun light.
2. Movement of an organism toward (positive) or away from (negative) sunlight.
3. Movement, as of a plant, in response to sunlight; heliotropism.
heterotaxia
1. An abnormal arrangement of organs or parts of the body in relation to each other.
2. Anomalous (abnormal) placement or transposition of viscera or parts.
3. An irregular or abnormal arrangement of parts or elements, i.e. in geological strata, body parts, etc.
heterotaxic
Abnormally placed or arranged.
homotaxis
1. A similarity of composition, arrangement, or fossil content among rock strata of different ages or locations.
2. Similarly in arrangement of parts; the opposite of heterotaxy.