PCS

*ḏḳn - to grow old (Kogan 2015: 428)

PS
*ḏaḳan- - beard (SED I No. 63, Kogan 2011: 223)

Hebrew
zāḳēn - of mature age, old (HALOT 278)
Old Aramaic
zḳn - to grow old (DNWSI 339)