from The Century Dictionary.
- noun The condition or state of being unicellular or consisting of a single cell, like the Protozoa and Protophyta.
Sorry, no etymologies found.
(Therefore X and Y are not necessary for unicellularity.) (2) Derived versions of genes X and Y are essential for multicellular life.
Bird Teeth 2008
The advance from unicellularity to multicellularity must have begun when cells divided and then remained clinging together.
The Human Brain Asimov, Isaac 1963