A separable verb is a verb that is composed of a lexical core and a separable particle. In some sentence positions, the core verb and the particle appear in one word, whilst in others the core verb and the particle are separated. The particle cannot be accurately referred to as a prefix because it can be separated from the core verb. German, Dutch, Afrikaans and Hungarian are notable for having many separable verbs. Separable verbs challenge theories of sentence structure because when they are separated, it is not evident how the compositionality of meaning should be understood.