Being in the centre.
Having or containing the centre of something.
Exerting its action towards the peripheral organs.
Being very important, or key to something.
centre
Being between two extremes, or in the middle of a range.
To mediate, to be an intermediate.
To arrange, in the manner of a broker.
Any substance formed as part of a series of chemical reactions that is not the end-product.
An intermediary.
Anything in an intermediate position.