The word "hammer oyster" is spelled as /ˈhæmər ɔɪstər/ in IPA phonetic transcription. The first syllable "ham" is pronounced with the same vowel as "cat" and ends with the consonant sound "m". The second syllable "mer" is pronounced with the same vowel as "fur" and ends with the consonant sound "r". The word "oyster" is pronounced with the vowel sound "oy" as in "boy" followed by the consonant sound "st" and the vowel sound "uh" as in "up". Together, the word "hammer oyster" refers to a type of oyster that is difficult to open and requires a hammer to break its shell.