means The tendency to feel nervous, awkward, or reserved in the presence of other people, especially strangers or in unfamiliar social situations.

from From "shy," an old Germanic word — Old English "sceoh," meaning skittish or easily startled, the same root that lets a horse "shy away" from a sudden movement. It's a cousin of German "scheu." The "-ness" suffix simply turns the quality into a thing you can have, so shyness is, at heart, the human version of a flinch.