Shoshin (say "show-shin") is what Shunryu Suzuki (say "shoon-ryoo soo-zoo-kee") called beginner's mind: the openness you have before you've decided you already know a thing. He didn't invent the idea, it traces back to older Zen usage, but his 1970 book made it famous in the West. His point isn't that experts know too much. It's that expertise quietly narrows what you're willing to notice, because the mind stops looking once it thinks it has already found the answer. A beginner sees many possibilities in the exact same room where an expert sees only the one familiar pattern. You already have a dozen expert routines before lunch: the commute, the login screen, the first exchange with a coworker. Pick one of them this morning and meet it as if you had never done it before, and see what you actually notice.
In the beginner's mind there are many possibilities, but in the expert's there are few.
Zen Mind, Beginner's Mind, Prologue (Shunryu Suzuki, 1970)