The spelling of the word "tooths nail" is incorrect. The correct form is "tooth's nail," with an apostrophe indicating possession. The phonetic transcription of "tooth's nail" is /tuθz neɪl/. The "th" sound is represented by "th," and the "s" sound indicating possession is represented by "s." The "n" sound in "nail" is represented by "n," and the "a" sound is represented by the letter "a." It is important to use correct spelling and pronunciation to ensure clear communication.