What is the definition best describes a base?

A base is a substance that can accept protons (H⁺ ions) or donate electron pairs in a chemical reaction. In aqueous solutions, bases typically increase the concentration of hydroxide ions (OH⁻). They often have a bitter taste and slippery feel, and they can neutralize acids to form salts and water. Common examples include sodium hydroxide (NaOH) and ammonium hydroxide (NH₄OH).