synaptic cleft

https://doi.org/10.1351/goldbook.12110
Narrow gap between the presynaptic and postsynaptic regions of two communicating neurons, into which neurotransmitters are secreted.
See also: synapse
Source:
PAC, 2015, 87, 841. (IUPAC Glossary of terms used in neurotoxicology (IUPAC Recommendations 2015)) on page 909 [Terms] [Paper]