-coccus(word root) spherical bacteriumExamples of words with the root -coccus: streptococcusAbused, Confused, & Misused Words by Mary Embree Copyright © 2007, 2013 by Mary Embree-coccussuff. A microorganism of spherical or spheroidal shape: streptococcus.[From coccus.]American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.coc?cus (?k?k ?s) n., pl. -ci (-s?, -s?). a spherical bacterium. [1755?65;