The Proto-Indo-European word *suhₓros
Word *suhₓros
Meaning sour, acid
Synonyms *kwat-, *h₂emros

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

Other words that might be of interest
*h₃em- ‘bitter’, *sweh₂d-u- ‘sweet’, *h₂em- ‘raw, bitter’, *(s)terh₁- ‘stiff’, *st(h₂)eug- ‘stiff’