la·bile 
(lābīl′, -bəl)
(lābīl′, -bəl)adj.
1. Open to change; readily changeable or unstable: labile chemical compounds; tissues with labile cell populations.
2. Fluctuating widely: labile hypertension; labile emotions.
3. Decomposing readily: the labile component of organic matter.
[Middle English labil, forgetful, wandering, from Old French labile, from Late Latin lābilis, apt to slip, from lābī, to slip.]
la·bili·ty (-bĭlĭ-tē) n.