Some common synonyms of applicable are apposite, apropos, germane, material, pertinent, and relevant. While all these words mean "relating to or bearing upon the matter in hand," applicable suggests the fitness of bringing a general rule or principle to bear upon a particular case.

// the rule is not applicable in this case

The words relevant and applicable are synonyms, but do differ in nuance. Specifically, relevant implies a traceable, significant, logical connection.

// found material relevant to her case

The meanings of apposite and applicable largely overlap; however, apposite suggests a felicitous relevance.

// add an apposite quotation to the definition