Related Clues:

• 55 Across, for example: Abbr.
• Part of MS
• Unwelcome plant?
• Poli-___ (college major)
• HS class
• MIT study
• Subject with projects: Abbr.
• Valerie Plame, e.g.
• Chem. or biol., e.g.
• Espionage expert
• Mole, e.g. 19. Thumbs-down vote
• Lab field: Abbr.
• Poly ___
• Double agent, e.g.
• U-2 pilot, e.g.