The transfer of powers from a central government to elected regional bodies within a unitary state, by ordinary law, so that the centre keeps the legal power to change or reverse it.
In more detail
The United Kingdom devolved powers in 1998 through separate acts for Scotland, Wales and Northern Ireland, with different arrangements for each. The Scotland Act 1998 created the Scottish Parliament but states that this does not affect Westminster's power to make laws for Scotland. Unlike federalism, devolved powers are not constitutionally entrenched against the centre.