Unicode character name for ǃ is LATIN LETTER RETROFLEX CLICK
The voiceless or more precisely tenuis (post)alveolar click is a click consonant found primarily among the languages of southern Africa. The symbol in the International Phonetic Alphabet that represents this sound is ⟨ǃ⟩. The Doke/Beach convention, adopted for a time by the IPA and still preferred by some linguists, is ⟨ʗ⟩.
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↑Kirshembaum assigns ⟨c!⟩ indifferently to both alveolar and palatal clicks.