labile

https://doi.org/10.1351/goldbook.L03432
The term has loosely been used to describe a relatively
unstable
and
transient chemical species
or (less commonly) a relatively
stable
but reactive species. It must therefore not be used without explanation of the intended meaning.
See also:
inert
,
persistent
,
reactive
,
unreactive
Source:
PAC, 1994, 66, 1077. (Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)) on page 1134 [Terms] [Paper]