Define synapse.

Explanation

### Step-by-Step Text Solution:

1. **Definition of Synapse**: A synapse is a specialized junction between two neurons or between a neuron and a target cell (such as a muscle or gland).

2. **Structure of Synapse**: The synapse consists of three main components:
- **Presynaptic Neuron**: This is the neuron that sends the signal. It has an axon terminal that contains neurotransmitter molecules.
- **Synaptic Cleft**: This is the small gap or space between the presynaptic neuron and the postsynaptic neuron. It is also referred to as the synaptic cleft.
- **Postsynaptic Neuron**: This is the neuron that receives the signal. It has dendrites that contain receptors for the neurotransmitters.
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