The spelling of the word "un alert" may seem confusing, but it can be explained through IPA phonetic transcription. The prefix "un" is pronounced as /ʌn/ which means "not" or "opposite of". The word "alert" is pronounced as /əˈlɜrt/ with the stress on the second syllable. Therefore, when the prefix "un" is added, the stress remains on the second syllable and it becomes "ʌn-əˈlɜrt". This means the opposite of being alert or not being attentive to one's surroundings.