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.
Being very important, or key to something.
Having or containing the centre of something.
Being in the centre.
Exerting its action towards the peripheral organs.
centre