- relevant - having a bearing on or connection with the subject at issue; "the scientist corresponds with colleagues in order to learn about matters relevant to her own research"
Antonyms: irrelevant, digressive, tangential, extraneous, immaterial, impertinent, orthogonal, inapplicable, unsuitable, moot
- crucial, relevant - having crucial relevance; "crucial to the case"; "relevant testimony"
Antonym: immaterial (indirect, via material)