The study of the change in proportion of various parts of an organism as a consequence of growth: Jack was interested in the field of allometry involving the extremities or organs of a living animal growing out of balance or proportion with the rest of its body.

Polymorphism in which the allometric regression line has a single slope; in ants use of the term also implies that the relation of some of the body parts measured is non-isometric.

Polymorphism in which the allometric regression line (study of the relative growth of a part of an organism in relation to the growth of the whole), when plotted on a double logarithmic scale, breaks at two points and consists of three segments.

In ants, the two terminal segments usually have slight to moderately high slopes and the middle segment has a very high slope.