ˈvälˌväks noun
Usage: capitalized
Etymology: New Latin, from Latin volvere to roll — more at voluble
: a genus of minute pale green flagellates that occur in spherical colonies about one fiftieth of an inch in diameter, that are propelled through water by means of minute colorless flagella which rotate the colony about an axis so that one end is constantly anterior, and that are treated as green algae and the type of the family Volvocaceae or as plantlike flagellates and the type of the family Volvocidae