What term describes a substance with a pH less than 7?

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pH indicates how acidic or basic a solution is: below 7 means acidic, 7 is neutral, and above 7 is basic. If a substance has a pH less than 7, it is described as an acid because acids increase hydrogen ion concentration in water, lowering the pH. The term that fits this property is acid. A base would have a pH greater than 7, neutral substances sit at about pH 7, and salts are products of acid–base reactions whose solutions can be acidic, basic, or neutral depending on the ions involved, so they are not defined by being under 7.