Related Clues:

• ___ lepton (physics particle)
• Bears' home, briefly
• Cross shape
• Greek T
• Greek antepenultimate
• See 41-Across
• Psi's preceder
• Windy City, for short
• ___ cross
• Standard deviation symbol
• 19th Greek letter
• Symbol of conductivity
• It's Greek to me
• X, as in Xenophon
• Letter from Athens