A mythical bird of prey having enormous size and strength: A winged roc with golden wings was featured in the myth about the sailors who were shipwrecked in the Aegean Sea.

1. A relatively hard, naturally formed mineral or petrified matter; stone: Andrew ordered a load of crushed rock to use in the driveway.
2. A naturally formed aggregate of mineral matter constituting a significant part of the earth's crust: The Laurentian Shield in Canada is a layer of granite rock in Northern Canada which makes it difficult for trees to grow.
3. Popular music which is typically amplified: Sabina and Steve were getting ready to attend a concert of rock at a club in the evening.
4. Used in phrases to say that something is hard, steady, reliable, etc.: Walter works out quite often at the fitness studio, which is why, when Jane touches his arm, she senses that it is almost as solid as a rock.

To shake or to move back and forth: Ryan's mother started to rock the baby to sleep while sitting in the rocking chair.