Accidental gap

In linguistics an accidental gap, also known as a gap, lexical gap, lacuna, or a hole in the pattern, is a word or other form that does not exist in some language but which would be permitted by the grammatical rules of the language. Accidental gaps differ from systematic gaps, those words or other forms which do not exist in a language due to the boundaries set by phonological, morphological, and other rules of that specific language.

In English, for example, a word pronounced /pfnk/ cannot exist because it has no vowels and therefore does not obey the word-formation rules of English. This is a systematic gap. In contrast, the string /peɪ̯k/ obeys English word-formation rules, but is not a word in English. Although theoretically such a word could exist, it does not; its absence is therefore an accidental gap.

Various types of accidental gaps exist. Phonological gaps are either words allowed by the phonological system of a language which do not actually exist, or sound contrasts missing from one paradigm of the phonological system itself. Morphological gaps are non-existent words potentially allowed by the morphological system. A semantic gap refers to the non-existence of a word to describe a difference in meaning seen in other sets of words within the language.

Often words that are allowed in the phonological system of a language are absent. For example, in English the consonant cluster /spr/ is allowed at the beginning of words such as spread or spring and the syllable rime /ɪk/ occurs in words such as sick or flicker. Even so, there is no English word pronounced */sprɪk/. Although this potential word is phonologically well-formed according to English phonotactics, it happens to not exist.

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