secondary growth

This term is a specialized botanical expression used primarily in plant biology and forestry. It describes the lateral expansion of a plant, contrasting with primary growth, which refers to the elongation of the plant's height or length at the tips of stems and roots.

Because it refers to a biological process or a specific physiological phenomenon, it is treated as an uncountable noun. It is not used to describe individual instances of growth but rather the systemic mechanism of thickening in woody plants.