Explanation:

- Infinite: This word refers to something that has no end or limit—endlessly large or boundless.

- Option 1 - Boundless: This describes something without limits, similar to infinite. It is not an antonym.

- Option 2 - Eternal: This implies something lasting forever, which aligns with the idea of infinity. Hence, it is not an antonym.

- Option 3 - Vast: This indicates something very large in size or amount. Although large, it does not imply infinity and is not opposite to infinite.

- Option 4 - Limited: This means having restrictions or bounds, which is directly opposite to the definition of infinite.