Tending to move toward a center.

Roget 290: converging etc. v.; convergent, confluent, concurrent; centripetal; asymptotical, asymptotic; confluxible^†.   

Roget 289: repelling etc. v.; repellent, repulsive; abducent^†, abductive^†.    centripetal

Tending to unify.

synoniem: unifying.

Of a nerve fiber or impulse originating outside and passing toward the central nervous system.

synoniemen: receptive, sensory.