Definition of "cankerworm"

cankerworm

noun
plural cankerworms
1. Either of two caterpillars, the larvae of geometrid moths, that are destructive to fruit, buds and leaves.
2. (figurative) A corrupting or destructive force.
  Quotations
  O cursed Eld the cankerworme of writs, / How may these rimes, so rude as doth appeare, / Hope to endure, sith workes of heauenly wits / Are quite deuourd, and brought to nought by little bits?
  1596, Edmund Spenser, “Book IV, Canto II”, in The Faerie Queene. […], London: […] [John Wolfe] for William Ponsonbie