What growth is
Saying that "growth" means getting bigger is not enough. In biology it has a definite meaning.
Cell growth
Cell growth is the irreversible increase in the dry weight of a living cell.
Both words matter
Irreversible
It cannot be undone. A plant swelling as it takes up water is not growth — lose the water and it returns to what it was.
Dry weight
The weight of what is left once the water is driven off. Unless real material rather than water has been added, the dry weight does not rise.
Growth happens in two ways
The size and volume of the cell itself increase. Examples — Paramecium, yeast, Chlamydomonas.
The main contribution is the number of cells increasing through cell division.