At a synapse, the plasma membrane of the signal-passing neuron (the presynaptic neuron) comes into close apposition with the membrane of the target (postsynaptic) cell.
In many synapses, the presynaptic part is located on an axon and the postsynaptic part is located on a dendrite or soma.
Synapse (Wikipedia) In the nervous system, a synapse is a structure that permits a neuron (or nerve cell) to pass an electrical or chemical signal to another neuron or to the target effector cell.