The spelling of the two-word phrase "is tail" is fairly straightforward. The first word "is" is spelled as it sounds, with the short i sound followed by the s sound. The second word "tail" is spelled with a long a sound followed by the l sound. The IPA phonetic transcription of "is tail" would be /ɪs teɪl/, with the stressed syllable being on the second word "tail". Overall, the spelling of this phrase is intuitive and easy to understand.