The phrase "bob under" is spelled phonetically as /bɑb ˈʌndər/. The word "bob" is spelled with a single "b," and the "o" sound is pronounced as /ɑ/. The word "under" is spelled with a "u" and an "n," and the "e" is pronounced as /ə/. Together, the phrase means to dip or submerge oneself under water briefly. The spelling of "bob under" accurately represents its pronunciation and can aid in understanding and communicating the word effectively.