The ⚀quadcia·lengthel, or ⚀luminal·length
The fourth negative dozenal power of the ⚀lengthel, the ⚀quadcia·lengthel (abbreviated ⚀q↓lgℓ) is on the order of the wavelengths of visible light. As a consequence, a proposed colloquial name for this is the ⚀luminal·length.