It is unclear what the word "BETABUTX" means. However, its spelling can be explained using the International Phonetic Alphabet (IPA). The first two letters, "BE," are phonetically transcribed as /biː/. The following letters, "TA," are transcribed as /tɑː/. The next four letters, "BU," are transcribed as /bʌ/. The letter "T," which comes next, is transcribed as /t/. Finally, the letter "X" is transcribed as /ks/. Therefore, the phonetic transcription of "BETABUTX" is /biːtɑːbʌtk.s/.