To be
thrust or
plunged forward or downward. To do something
unexpected, to plunge into
something. To
descend or
dip suddenly.
Also, Plunge is the name of one of my favorite jazz bands. They have an album, Falling with Grace, out on Accurate Records. They are currently a three-piece, with Mark McGrain on trombone, Kirk Joseph on tuba, and Bob Moses on drums. They are heavy on the bottom end.