What does "scratch the surface" mean?

To barely begin; to see or do only a fraction of what is possible.

What is a synonym for "scratch the surface"?

Common synonyms include: be innocent of, coquet with, dabble, give up, have no idea, hit the high spots.

verb

verb ·Rare ·Advanced level

Verb

1
To barely begin; to see or do only a fraction of what is possible. idiomatic
"This beginners' course only scratches the surface of the subject."

"This beginners' course only scratches the surface of the subject."