If you mean "pail" as in a container:
* Bucket: This is the most common synonym, and therefore the closest you'll get to an antonym.
* Tub: Larger and deeper than a pail.
* Crate: A rigid container, often used for storage.
* Barrel: A large, cylindrical container.
If you mean "pail" as in "pale" (meaning lacking color):
* Vibrant: Full of life and color.
* Bright: Shining with light.
* Colorful: Having many colors.
If you mean "pail" as in "pallid" (meaning pale in complexion):
* Ruddy: Having a healthy reddish complexion.
* Rosy: Having a pink or rosy complexion.
* Tanned: Having a brown skin tone from sun exposure.
Please provide more context if you need a more specific antonym.