Welcome to Visual Dictionary, a series of posts about words that are better expressed in pictures.

This is a cog. It is a small gearwheel.

Actually, the little teeth (“tenons”) coming out of it are called cogs, and the whole thing is can be called a cogwheel, but when most people say cog, especially in a metaphorical way, they mean the whole thing, the cogwheel.

In a literal sense, a cog or cogwheel “transmits successive motive force to a corresponding wheel or gear.” Usually, a lot of cogs work together, such as in this clockworks:

Metaphorically speaking, a cog is a person in a company or organization who does very routine tasks. If you’re a cog, you might be doing necessary work, but you might feel as though anyone could do your job, and as though you are not very significant. No one wants to be “a cog in the machine.”

Try this sample Antonyms problem:

COG :
A. TOADIE
B. WRENCH
C. DIRECTOR
D. PHILATELIST
E. LIBERTINE

Choose your own answer, then click “more.”

A cog is a physical object, but physical objects rarely can be said to have antonyms, so we probably want to use the stem in the sense of “a person who performs minor, routine tasks.” The opposite of that would be something like a boss or overseer. The answer is C, DIRECTOR.

By the way, a toadie is a servile flatter (a “kiss-up”), a wrench is just the thing in your toolbox, a philatelist is a stamp collector, and a libertine is a party animal.

Manhattan GRE’s blog is written by one of our real-live GRE instructors. She teaches in New York. To learn about Manhattan GRE’s classes, go here. To suggest a word or topic for the blog, email jenniferd@manhattangmat.com.