Meaning of "The better part of the day"

[Tom]

Hi

Please see below:

1- He had slept the better part of the day.

Does it mean that he had slept most of the day? Could I use this expression in my everyday English?

Tom

[Yankee]

Hi Tom

The better part of something is more than half of something. But how much more than half is unclear. So, yes, it could also mean most of

This is a very normal expression and also appropriate for everyday English.

Amy