The word "obtuser" refers to something that is dull or less sharp. The spelling of this word is [əbˈtjuːsər], which is phonetically represented as uhb-too-zer. The initial "o" sound is replaced by a schwa sound [ə], while the "b" and "t" sounds are voiced [b] and [dʒ]. The final "r" sound is replaced by a voiced "z" sound. Overall, the phonetic transcription accurately reflects the pronunciation of this adjective.