The voiceless or more precisely tenuis retroflex click is a rare click consonant. In practical orthography, an ad hoc symbol ⟨‼⟩ is used for the retroflex clicks; a tenuis click with a velar rear articulation is ⟨k͡‼⟩ or ⟨k͜‼⟩, commonly abbreviated to ⟨k‼⟩, ⟨ᵏ‼⟩ or just ⟨‼⟩.
The implicit symbol in the International Phonetic Alphabet is ⟨k͡⟩ or ⟨k͜⟩, abbreviated ⟨k⟩, ⟨ᵏ⟩ or just ⟨⟩. Linguists who prefer the old IPA letters use the analogous Doke convention of ⟨k͡ψ⟩ or ⟨k͜ψ⟩, abbreviated ⟨kψ⟩, ⟨ᵏψ⟩ or ⟨ψ⟩. For a click with a uvular rear articulation, the equivalents are ⟨q͡‼, q͜‼, q‼, ‼⟩, ⟨q͡, q͜, q, ⟩ and ⟨q͡ψ, q͜ψ, qψ, ψ⟩.
Sometimes the accompanying letter comes after the click letter, e.g. ⟨k⟩ or ⟨ᵏ⟩; this may be a simple orthographic choice, or it may imply a difference in the relative timing of the releases.
The airstream mechanism is lingual ingressive (also known as velaric ingressive), which means a pocket of air trapped between two closures is rarefied by a "sucking" action of the tongue, rather than being moved by the glottis or the lungs/diaphragm. The release of the forward closure produces the "click" sound. Voiced and nasal clicks have a simultaneous pulmonic egressive airstream.