Why nuclear fusion is also known as thermonuclear reaction?

Explanation

### Step-by-Step Solution:

1. **Definition of Nuclear Fusion**:
Nuclear fusion is the process in which two light atomic nuclei combine to form a heavier nucleus. This process releases a significant amount of energy.

2. **Understanding the Term 'Thermo'**:
The prefix 'thermo' refers to heat. In the context of nuclear fusion, it indicates that the reaction is related to high temperatures.

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