Comparative evidence

kerḱ, kʷerḱ

• OInd. kṛś- 'be lean' (Whitney 1885: 23); 'be thin', 'become emaciated', 'become feeble'; 'cause to wane'; 'lessen', 'diminish' (MW: 305)

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.