Comparative evidence

1.ḱeu̯k

• OInd. śuc- 'gleam' (Whitney 1885: 174); 'shine', 'flame', 'glow', 'burn'; 'suffer violent heat', 'suffer pain', 'be sorrowful', 'be afflicted', 'grieve', 'mourn' (at or for); 'bewail', 'lament', 'regret'; 'be absorbed in deep meditation'; 'be bright', 'be pure'; 'be wet'; 'decay', 'be putrid', 'stink' (MW: 1081)

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.