sqare
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.
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.
any 4 sided 2d shape * * * * * Mathematically, any plane shape, no matter how many sides.
Irregular or without a definite shape.
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.
Yes
a shape that has a length and height, but no width.
It normally defines the shape of an object