Definitions for "Acid-base indicator"
A weak acid or weak base, such as litmus or phenolphthalein, which changes color when it gains or loses an H+ ion.
an acid-base conjugate pair, a weak acid-weak base system in which the two forms have different colors
a weak acid having a different colour in aqueous solution from its conjugate base
an indicator that changes color on going from acidic to basic solutions
a chemical that changes color depending on its environment