Wiktionary
multicellularity
n. The condition of being multicellular.
Usage examples of "multicellularity".
The advance from unicellularity to multicellularity must have begun when cells divided and then remained clinging together.
The mere act of clinging together, as in seaweeds, involves no true multicellularity, however.
True multicellularity requires the establishment of a "cellular society" with needs that overbalance those of the individual cell.