= Semiclassical approximation
A <semiclassical approximation> describes a <quantum system> in a regime where classical actions are large compared with $\hbar$, while retaining selected quantum corrections. In one-dimensional WKB theory, a local <wavefunction> has phase approximately $\hbar^{-1}\int p(x)dx$ and <amplitude> proportional to $|p(x)|^{-1/2}$ away from <turning points>.
The approximation exposes classical trajectories and phases without discarding <interference>. It fails near a <turning point> where $p=0$, requiring a different local solution and matching. Semiclassical therefore names a controlled approximation regime and method, rather than simply replacing every quantum quantity by a classical one.
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