1N-COUNT （嵌）齿轮 A cog is a wheel with square or triangular teeth around the edge, which is used in a machine to turn another wheel or part. （嵌）齿轮
2PHRASE (大型机构或团体中的)一小分子 If you describe someone as a cog in a machine or wheel, you mean that they are a small part of a large organization or group. (大型机构或团体中的)一小分子
Mr Lake was an important cog in the Republican campaign machine.