Comparative evidence

ḱad

• OInd. śad- 'fall' (Whitney 1885: 170); 'fall off', 'fall down' (MW: 1051)

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.