Relevant, germane, material, pertinent, apposite, applicable, apropos are comparable when they mean having a relation to or a bearing upon the matter in hand or the present circumstances.
Something relevant has a traceable connection, especially logical connection, with the thing under consideration and has significance in some degree for those who are engaged in such consideration.
Something germane is so closely related (as in spirit, tone, or quality) to the subject, the matter, the occasion, or the issue that the fitness or appropriateness of their association is beyond question.
Something material is so closely related to the matter in hand that it cannot be dispensed with without having an evident and especially a harmful effect.
Something pertinent is so decisively or significantly relevant that it touches the real point at issue or contributes materially to the understanding of what is under discussion or to the solution of what is in question.
Something apposite is relevant and germane to such a degree that it strikes one both by its pertinency and by its felicitousness.
Something applicable may be brought to bear upon or be used fittingly in reference to a particular case, instance, or problem.
Something apropos is both appropriate and opportune.
Sometimes it can suggest relevancy rather than appropriateness or opportuneness.