Which of these is not a lipid?

Options

A. Steroid
B. Fat
C. Polysaccharide
D. Wax

Explanation

To determine which of the given options is not a lipid, let's analyze each option step by step:

1. **Steroid**:
- Steroids are a type of lipid. They are characterized by a hydrophobic nature and are insoluble in water. Their structure consists of four fused carbon rings. Therefore, steroids are classified as lipids.

2. **Fat**:
- Fats are also classified as lipids. Specifically, they are a subgroup of lipids known as triglycerides. Fats are composed of glycerol and fatty acids. Hence, fats are indeed lipids.

3. **Polysaccharide**:
- Polysaccharides are not lipids; they are carbohydrates. They are formed by the bonding of multiple monosaccharides (simple sugars) like glucose and fructose. Common examples of polysaccharides include starch and cellulose. Therefore, polysaccharides do not belong to the lipid category.

4. **Wax**:
- Waxes are also considered lipids. They consist of long-chain fatty acids linked to long-chain alcohols through ester bonds. Waxes serve various functions, including protection and waterproofing. Thus, waxes are classified as lipids.

Based on the analysis above, the option that is not a lipid is **polysaccharide**.

### Final Answer:
**Polysaccharide is not a lipid.**