Concept
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. The separation of such verbs is called tmesis. The German verb ankommen is a separable verb, and is used here as the first illustration: The first two examples, sentences a and b, contain the "simple" tenses. In matrix declarative clauses that lack auxiliary verbs, the verb and its particle (both in bold) are separated, the verb appearing in V2 position and the particle appearing in clause-final position. The second two examples, sentences c and d, contain the so-called "complex tenses"; they show that when an auxiliary verb appears, the separable verb is not separated, but rather the stem verb and particle appear together as a single word. The following two examples are from Dutch: The Dutch verb aankomen is separable, as illustrated in the first sentence with the simple present tense, whereas when an auxiliary verb appears (here is) as in the second sentence with present perfect tense/aspect, the lexical verb and its particle appear together as a single word. The following examples are from Hungarian: The verb letesz is separated in the negative sentence. Affixes in Hungarian are also separated from the verb in imperative and prohibitive moods. Moreover, word order influences the strength of prohibition, as the following examples show: English has many phrasal or compound verb forms that are somewhat analogous to separable verbs. However, in English the preposition or verbal particle is either an invariable prefix (e.g.