In this paper, we propose a dynamic and flexible approach to ontology modularization inspired by the aspect-oriented programming paradigm in software development. Aspect-oriented programming provides formalisms for encapsulating a software system's functionality in self-contained modules, where each module represents a single requirement, along with meta-information on how to recombine the modules at runtime. The recombination requires second-order reasoning, but it can be shown that it is sufficient to interpret the second-order constructs under a Henkin semantics, reducing the problem to first-order logic. We demonstrate the applicability of the approach to the problem of modular ontologies by presenting a proof-of concept implementation for aspect-oriented OWL 2 ontologies. Furthermore, we show that the approach can be used as a substitute for metamodeling and may be helpful in preventing expensive refactoring operations in certain ontology integration scenarios.