plunge

1 to cast oneself head first into deep water she took a deep breath and plunged from the side of the pool Synonyms pitch, dive, soundRelated Words dip, immerse, submerge; belly flop, plump, plunk (or plonk)Near Antonyms surface

2 to go to a lower level especially abruptly prices for those televisions have really plunged since they were first introduced Synonyms crash, crater, decline, descend, dip, dive, fall, lower, nose-dive, plummet, drop, sink, skid, tumbleRelated Words abate, decrease, de-escalate, die (down), diminish, droop, dwindle, ebb, lessen, let up, moderate, subside, taper off, wane; recede, retreatNear Antonyms accumulate, balloon, build, burgeon (also bourgeon), enlarge, escalate, expand, grow, increase, intensify, mushroom, pick up, snowball, swell, waxAntonyms arise, ascend, lift, mount, rise, soar, spike, up

3 to lead or extend downward a stairway plunging into darkness Synonyms decline, dip, drop, fall, descend, sinkRelated Words angle, cant, cock, heel, incline, lean, list, recline, slant, slope, tilt, tipNear Antonyms even, flatten, level, plane, smooth, straightenAntonyms arise, ascend, climb, mount, rise, uprise, upsweep, upturn