Apropos
Part of speech: adjective
Definition: Of an appropriate or pertinent nature.
Part of speech: preposition
Definition: Regarding or concerning.
Part of speech: adverb
Definition: “By the way”. timely, at a good time.
Apposite
Part of speech: adjective
Definition: appropriate, relevant, well-suited; fitPositioned at rest in respect to another, be it side-to-side, front-to-front, back-to-back, or even three-dimensionally: in apposition.
Part of speech: noun
Definition: Something that is apposite