An opaque body that neither reflects nor transmits the incident heat radiations but absorbs thermal radiations of all wavelengths falling on it, is called a ................ body.

Explanation

To solve the question, we need to identify the term that describes an opaque body which absorbs all incident thermal radiations without reflecting or transmitting any of it. Here’s the step-by-step solution:

### Step 1: Understand the properties of the body
The question describes a body that:
- Is opaque (does not allow light or heat to pass through)
- Does not reflect incident heat radiations
- Does not transmit incident heat radiations
- Absorbs thermal radiations of all wavelengths
...