D defs.my
Entry 3 senses Webster, 1913

breakthrough

· break·through · IPA /ˈbɹeɪk.θɹuː/
01 n. a productive insight.
  1. 1.
    a productive insight.
  2. 2.
    a sudden change of situation, such as making an important discovery, that permits further rapid advances toward a goal.
  3. 3.
    a penetration of an enemy's defense in depth and strength.(Mil.)
Syn. discovery, find.