The word "rock" has a few different meanings:

When used as a noun, the word "rock" refers to a hard geological formation that is millions of years old.
 As a form of music, rock is played with one or two guitars, a set of drums, and, perhaps, a bassist.
rock guitar

 When a baby is crabby or crying, a mother rocks the baby to sleep in her arms. This is a back-and-forth movement.

She rocked the baby to sleep.

rock a baby

 Many back-and-forth movements are described with the word "rock."

You can rock back and forth in a rocking chair.

rocking chair
 But if you aren’t careful and you stand up in a boat, a rocking movement can cause you to lose your balance, and you’ll end up in the water.
rock the boat

There are a lot of expressions that use the word "rock."

  • Don’t rock the boat. (Don’t cause any problems.)
  • This bread is hard as a rock. (It’s very hard.)
  • He’s dumber than a box of rocks. (He’s very stupid.)
  • This building is as steady as a rock. (It has a good foundation; it’s well made; it won’t fall over.)
  • You rock! (You’re a great person!)
  • This Thai food rocks. (It’s very good)
  • We’ve got to rock. See you tomorrow. (rock = leave)
  • The party was really rocking past midnight. (There were a lot of people there.)

Note: Rock’n’roll music has had a powerful effect on American culture and English language over the last fifty years. You should learn a little about this form of music if you don’t already. In conversation, the word "rock" often comes up as a verb or as an adjective.

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This page was first published on November 5, 2012. It was updated on December 23, 2015.