Lability

For the psychological term, see Labile affect.

Lability refers to something that is constantly undergoing change or something that is likely to undergo change.

Chemistry

The term is used to describe a relatively unstable and transient chemical species. As a general example, if a molecule exists in a particular conformation for a short life-time, before adopting a lower energy conformation, the former molecular structure is said to have 'high lability' (such as C₂₅, a 25-carbon fullerene spheroid). The term is sometimes also used in reference to reactivity - for example, a complex that quickly reaches equilibrium in solution is said to be labile (with respect to that solution). Another common example is the cis effect in organometallic chemistry, which is the labilization of CO ligands in the cis position of octahedral transition metal complexes.

Biochemistry

In reference to biochemistry, this is an important concept as far as kinetics is concerned in metalloproteins. This can allow for the rapid synthesis and degradation of substrates in biological systems.

Biology

Cells

Labile cells refer to cells that constantly divide by entering and remaining in the cell cycle. These are contrasted with "stable cells" and "permanent cells".

An important example of this is in the epithelium of the cornea, where cells divide at the basal level and move upwards, and the top-most cells die and fall off.

Proteins

In medicine, the term "labile" means susceptible to alteration or destruction. For example, a heat-labile protein is one that can be changed or destroyed at high temperatures.

The opposite of labile in this context is "stable."