I would just use "dead code elimination" instead. They're the same but that actually tells you what it is.
Dead code elimination in its traditional form also runs during code minification, which is a separate build step from bundler tree shaking. Having separate terms avoids ambiguity.
A practical example would be that tree-shaking wouldn't remove the variable b in "export function foo(x) { let b = 10; let a = 20; return x + a; }" but if this export isn't imported anywhere, then it would remove the whole function definition. Uglify.js, which does dead code elimination would remove the unused b variable.