to plunge into water head foremost; to thrust the body under, or deeply into, water or other fluid.-fig.: to plunge or to go deeply into any subject, question, business, etc.; to penetrate; to explore.-to plunge (a person or thing) into water; to dip; to duck.-to explore by diving; to plunge into.-a plunge headforemost into water, the act of one who dives, literally or figuratively.-a place of low resort.