Convergence
Convergence is when many presynaptic neurons send signals, by using neurotransmitters, to a single postsynaptic neuron[1]. This is the opppsite of divergence, where the signal is sent from a single presynaptic neuron to many postsynaptic neurons.
References
1. Alberts B, Bray D, Hopkins K, Johnson A, Lewis J, Roberts K et al. Essential cell biology. 3rd ed. New York: Garland Science; 2010.