The word "preextent" is not a commonly used word, but it does have a valid spelling. The IPA phonetic transcription of this word is /priːɪkstɛnt/. From this, we can understand that the first syllable is pronounced "pre-", as in "previous". The second syllable is pronounced "ex-", as in "exit", and the third syllable is pronounced like "tent", as in a camping tent. Put together, "preextent" means something that extends before something else.