Strikingly appropriate or relevant; well suited to the circumstance or in relation to something.
Positioned at rest in respect to another, be it side-to-side, front-to-front, back-to-back, or even three-dimensionally: in apposition.
Related, homologous.
That which is apposite; something suitable.
Of a sentence or utterance: semantically and pragmatically coherent; fitting in the context.
Auspicious, fortunate, lucky.
Causing happiness or pleasure.
Appropriate, apt, fitting.