aux(o)-

Growth or increase.

Greek auxein, to increase.

An auxin is a plant hormone which regulates plant growth; an auxotroph (Greek trophos, feeder) is an organism that needs special nutrients to grow; auxesis is growth that results from an increase in cell size rather than of the number of cells; an auxochrome is a group of atoms introduced into a dyestuff to intensify its colour. Auxiliary, however, comes from Latin auxilium, help.