A substance that does not have a fixed crystalline shape is called _________

Explanation

**Step-by-Step Text Solution:**

1. **Understanding the Question**: The question asks for the term used to describe a substance that lacks a fixed crystalline shape.

2. **Defining Crystalline and Amorphous**:
- Crystalline substances have a well-defined geometric shape and a regular arrangement of particles.
- Amorphous substances, on the other hand, do not have a regular arrangement of particles and therefore do not form a fixed shape.

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