The baby birds slept soundly.

Meaning: Young birds are in a state of deep and peaceful sleep.

Choice of Words: Soundly means in a deep and peaceful sleep. The sentence describes baby birds sleeping deeply and peacefully.

Alternative Expressions

The little birdies were fast asleep.

Meaning: This sentence also describes how baby birds are sleeping peacefully, but it uses different words to convey the same idea.

Choice of Words: The word little is used to describe something that is small. Birdies is a friendly way to refer to birds. Fast asleep means to be sleeping deeply.

The baby birds were sleeping like logs.

Meaning: This sentence describes how baby birds are sleeping so deeply that they are not easily woken up.

Choice of Words: The word logs refers to pieces of wood that are cut from trees. Logs are often used to build things or to burn for heat. When we say someone is sleeping like a log, we mean that they are sleeping very deeply and soundly.

Related Expressions