ˌ ̷ ̷ ̷ ̷ˈkäkəs noun
Usage: capitalized
Etymology: New Latin, from prot- + -coccus
: a genus of unicellular globose chiefly terrestrial green algae (family Protococcaceae) that in former classifications included most such aerial algae but is now usually restricted to forms with a single large peripheral cloroplast that divide in two planes to form thin filmy colonies (as on damp rocks or the bark of trees) — compare chlorococcum