lability

Lability is the quality of being labile, or easily altered or unstable. It is used across disciplines to denote a tendency to change in response to internal and external conditions, and to distinguish between states or components that are readily affected and those that are more stable.

In psychology and medicine, affective lability refers to rapid, exaggerated, and frequent changes in emotional states. It is a feature of several psychiatric and neurological conditions and may accompany mood disorders, frontal lobe injury, and some personality disorders. The term is also applied to fluctuating physiological measurements, such as labile blood pressure or labile glucose levels, which can complicate diagnosis and management.

In chemistry and biochemistry, labile describes chemical species or bonds that readily undergo transformation or exchange. A labile ligand in a coordination complex is replaced quickly; labile protons or hydrogens are easily donated. The concept helps distinguish reactive or rapidly exchanging processes from more inert, kinetically stable ones, and it is important in fields such as catalysis, enzymology, and pharmacology.

In biology, ecology, and environmental science, lability can refer to the plasticity of traits, gene expression, or ecosystem responses. Genetic lability indicates a propensity for rapid genotype changes under stress, while ecological lability denotes swift shifts in community composition or function. In soil science, labile nutrient fractions are those readily available for uptake or mobilization, such as labile phosphorus.