Extra-shortness
The International Phonetic Alphabet uses a breve to indicate a speech sound with extra-short duration. That is, is a very short vowel with the quality of. An example from English is the short schwa of the word police. This is typical of vowel reduction.
Before the 1989 Kiel Convention, the breve was used for a non-syllabic vowel, which is now indicated by an breve placed under the vowel letter, as in eye. It is also sometimes used for any flap consonants missing dedicated symbols in the IPA, since a flap is in effect a very brief stop.
