An Acid is a Corrosive solution with a pH less than 7.

Further definition:
An Acid is a solution that has a pH value lower than 7

---> see also:
"Acid" is in the HS Code "3204.12"
  - -- Acid dyes, whether or not premetallised, and preparationsbased thereon; mordant dyes and preparations based thereon

"Acid" is in the UNSPSC Code "12164102"
  Acid additives

---> see also:
"Acid" is in the HS Code "2924"
  Carboxyamide-Function Compounds; Amide-Function Compounds Of Carbonic Acid

"Acid" is in the UNSPSC Code "12161704"
  Acid buffers