Understanding the Word POROUS

The question asks us to find the most appropriate antonym for the word POROUS.

Let's first understand what the word POROUS means. Something that is porous has tiny holes or spaces through which liquid, air, or light can pass.

Think of a sponge or a sieve; they are porous because they have many small holes.

Analyzing the Options

Now, let's look at the given options and their meanings:

1. impermeable: This word describes something that does not allow liquid or gas to pass through it.
2. absorbent: This word means capable of soaking up liquid. While porous materials are often absorbent, being absorbent is a consequence of having pores, not the definition of being porous itself.
3. spongy: This word describes something that is soft and elastic, like a sponge, typically because it is full of holes and can soak up liquid. This is very similar in meaning to porous.
4. permeable: This word means allowing liquids or gases to pass through. This is a synonym for porous.

Finding the Antonym

We are looking for the word that means the opposite of POROUS (allowing things to pass through). Based on the meanings we just discussed:

• impermeable means preventing things from passing through.
• absorbent is related but not the direct opposite of having pores.
• spongy is similar to porous.
• permeable is a synonym of porous.

Therefore, the word that is the direct opposite, or antonym, of POROUS is impermeable.

Detailed Comparison

From the table, it is clear that impermeable is the word that means the opposite of allowing things to pass through small holes, which is the definition of POROUS.

Conclusion on the Antonym of POROUS

The word POROUS describes materials that have small holes allowing passage. The word that describes materials that do not allow passage is impermeable. Therefore, impermeable is the most appropriate antonym.

Revision Table: Key Vocabulary

Additional Information on Permeability and Porosity

While often related, porosity and permeability are distinct concepts, especially in fields like geology or material science:

• Porosity is a measure of the void spaces (pores) in a material. It is expressed as a fraction or percentage of the total volume. A material can be highly porous but not permeable if the pores are not connected.
• Permeability is a measure of the ability of a material to allow fluids (liquids or gases) to pass through it. This depends on the interconnectedness of the pores. A material with connected pores is permeable. A material with unconnected pores is impermeable, even if it has high porosity.

In the context of a general vocabulary question, 'porous' implies permeability. Thus, its antonym is a word that signifies the lack of permeability, which is 'impermeable'.