mathematically
In soccer, the "football" is what they call the specific type of ball used in the game. The Laws of the Game define the exact size, shape, material, and pressure that is to be used.
Liquid
None. It is mathematically impossible.
plasma
any 4 sided 2d shape * * * * * Mathematically, any plane shape, no matter how many sides.
liquid has a definite volume and takes on the shape of its container.
The two foci are necessary to define the location of an ellipse, but the shape depends on the eccentricity, which is related to the lengths of the two axes.
I was thinking about that myself, recently. The answer is "egg shaped". Mathematically, it's an "ovoid". Eggs vary in shape and there is no exact "formula" for the shape of an egg.
Irregular or without a definite shape.
Yes
A liquid has a define shape but a gas has no define shape