  We introduce the class of quasiconvex Lipschitz domains, which covers both
$C^1$ and convex domains, to the study of boundary unique continuation for
elliptic operators. In particular, we prove the upper bound of the size of
nodal sets for Dirichlet eigenfunctions of general elliptic equations in
bounded quasiconvex Lipschitz domains. Our result is new even for Laplace
operator in convex domains.
