The Proto-Indo-European word *sakros
Word *sakros
Meaning holy
Synonyms *k̂wen(to)-, *dʰēh₁-s(-io-), *noibʰos

Comments
Mallory J.P. and Adams D. (2006)

Other words that might be of interest
*deiwós ‘god’, *hₐénsus ‘god, spirit’