Labile is an adjective used to describe something that is easily or frequently changed. Radioactive elements, such as uranium or plutonium, are labile. It is this lability that makes them unstable and dangerous.
From the Latin verb lābī, "to slide or slip," labile is often found in a technical context, especially in science, to refer to some sort of instability. For example, in chemistry, a compound that can be easily broken down by heat is called labile. The term can also be used in psychology to describe someone who is emotionally unstable.