1. Referring to or related to the construction of something; such as, a building: "They made some structural repairs of the bridge."
2. Concerned with the systematic structure or aspects of a particular field of study.
3. The organization of people in a society considered as a system organized by a characteristic pattern of relationships.
4. Referring to or relating to the structure and deformation of rocks and other features of the earth's crust.

In geology, the scientific discipline that is concerned with rock deformation on both a large and on a small scale: The scope of structural geology is vast, ranging from submicroscopic lattice defects in crystals to fault structures and fold systems of the Earth’s crust.

Methods of structural geology

Small-scale structural features may be studied using the same general techniques that are employed in petrology, in which sections of rock mounted on glass slides are ground very thin and are then examined with polarizing microscopes.

On a larger scale, the techniques of field geology are used which include plotting the orientation of such structural features as faults, joints, cleavage, and small folds.

In most cases, the objective is to interpret the structure beneath the surface by using information available at the surface.

Where mountains, continents, ocean basins, and other large-scale features are involved, the methods employed are chiefly those of geophysics and include the use of seismological, magnetic, and gravitational techniques.