An Arrhenius acid refers to a component, which dissociates in water to produce hydrogen ions, or it can also be stated as that the acid enhances the concentration of hydrogen ions in an aqueous solution. On the other hand, an Arrhenius base refers to a component, which gets dissociate in water to produce hydroxide ions, or it can be said that a base enhances the concentration of hydroxide ions in an aqueous solution.
Therefore, an aqueous solution of lithium hydroxide comprising hydroxide ions as the sole negative ion in the solution is classified as an Arrhenius base.