While in some cases nearly identical to relevant, 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

Although the words pertinent and relevant have much in common, pertinent stresses a clear and decisive relevance.

// a pertinent observation

Some common synonyms of relevant are applicable, apposite, apropos, germane, material, and pertinent. While all these words mean "relating to or bearing upon the matter in hand," relevant implies a traceable, significant, logical connection.

// found material relevant to her case