What is the definition of acid?

Answer 1

The quality of being sour; sourness; tartness; sharpness to the taste; as, the acidity of lemon juice.

Answer 2

There are many definitions of acid but I will give only the best ones I feel -

1. I molecule or other species which can donate a proton or accept an electron pair in reactions.

The 2nd one is the perfect one I feel

2. A substance with particular chemical properties including turning litmus red, neutralizing alkalis, and dissolving some metals; typically, a corrosive or sour-tasting liquid of this kind.

Answer 3

a substance with a pH greater than 7. ie from 7 to 14

Answer 4

As a basic definition, an acid is defined as any substance in which its pH is less than 7. An acid can also be any substance which neutralizes a base solution (pH<7).