noun. Any of various unicellular green algae of the genus Chlorella.

noun. A genus of unicellular grass-green algæ occurring in symbiotic relationship with Hydra, Paramœcium, Ophrydium, and similar forms; the ‘yellow cell’ of Radiolaria.

noun. Any single-celled green alga, of the genus Chlorella, found especially in stagnant water; now produced commercially as a food supplement.

noun. any alga of the genus Chlorella

"In addition, one should take chlorella, which is a single-celled algae that is loaded with easily assimilable vitamins, minerals, and antioxidants."

alga  algae