Big-time (adverb)

1. To a significant or large extent; on a grand scale.
2. To a great degree; with great success or importance.

Origin:

This phrase is believed to have originated in the us in the early 20th century.

Examples:

1. He was playing big-time when he made that shot.
2. She was going big-time with her new job.
3. He was a big-time movie star.
4. She was a big-time celebrity.
5. It was a big-time event with a lot of people.