All of the books/online sources that I have found cite the following definition of the unit cell of a lattice :
The unit cell is defined as the smallest repeating unit having the full symmetry of the crystal structure.
My question is that all they have mentioned is the word 'small' without giving additional details about it like 'small in terms of what?'. Is it in terms of volume/area, number of lattice points in it or is it anything else?
I think that it is in terms of volume because when we reject 'end centered cubic' to be actually ' primitive tetragonal' the number of lattice points remain same but volume decreases however I would still like to confirm.