Definition of "moly"

It excels Homers moly, cures this, falling sickness, and almost all other infirmities.

1624, Democritus Junior [pseudonym; Robert Burton], The Anatomy of Melancholy: […], 2nd edition, Oxford, Oxfordshire: Printed by John Lichfield and James Short, for Henry Cripps, partition II, section 4, member 1, subsection iii

Or, propt on beds of amaranth and moly, / How sweet (while warm airs lull us, blowing lowly,)

1832 December (indicated as 1833), Alfred Tennyson, “The Lotos-Eaters”, in Poems, London: Edward Moxon, […], page 114

So spoke the Radiant One; then gave me the magic herb, pulling it from the ground and showing me in what form it grew; its root was black, its flower milk-white. Its name among the gods is moly.

1980, Walter Shrewing, translated by Homer, The Odyssey, Oxford, published 1998, page 120

The fuselage and tail unit were constructed of welded chrome-moly steel tubing, fabric covered, with two seats in one elongated open 'bathtub' cockpit.

1990, John Wegg, General Dynamics Aircraft and Their Predecessors, page 55