Comparative evidence

dei̯h₁

• OInd. -dī ‘soar’, ‘fly’, ‘fly away’ (MW: 480; Whitney 1885: 74)

Whitney 1885: 74: “Represented later by ḍī-. From it may possibly come didyú [«a missile, weapon, arrow; the sky, heaven»]”.

References

MW = Monier-Williams, M. 1899. A Sanskrit-English Dictionary. Clarendon Press.
Whitney 1885 = Whitney W. D. 1885. The roots, verb forms and primary Derivatives of the Sanskrit language. A supplement to his Sanskrit grammar. Leipzig.