plummet UK /ˈplʌmɪt/US /ˈplʌmət/noun 5verb 1forms 5 noun5 •A violent or dramatic fall. •(figurative) A decline; a fall; a drop.Yet another seriously under-par performance is unlikely to provide any real answers to their remarkable plummet in form - but it proves they can at least churn out a much-needed result. — 2010 •(no longer used) A piece of lead attached to a line, used in sounding the depth of water; a plumb bob or a plumb line.I'le seeke him deeper than ere plummet sounded, / And with him there lye mudded. — 1610 •(no longer used) Hence, any weight.His parachute was shot half away, and if he'd jumped he would have fallen like a plummet. — 1945 •(no longer used) A piece of lead formerly used by schoolchildren to rule paper for writing (that is, to mark with rules, with lines). verb1 •To drop swiftly, in a direct manner; to fall quickly.After its ascent, the arrow plummeted to earth. formsplummeted · plummetted · plummeting · plummetting · plummets