Copyright law defines derivative work by substantial similarity and dependence, not by technical mechanisms like linking. Technical measures such as linking is not a copyright concept.

Dynamic linking is a condition for LGPL compliance, but it is not sufficient. Dynamic linking does not automatically prevent a combined work from being a derived work.

> Dynamic linking is a condition for LGPL compliance

No, it isn’t. The condition says to allow your users to make and use their own modifications to the part of the software which falls under the LGPL. Dynamic linking is only a convenient way of allowing this, not a requirement.