1. Concave on both sides
   - biconcave

See also: concave

• Simchas Torah
• Simchat Torah
• Simenon
• Simeon
• Simhat Torah
• Simhath Torah
• simian
• similar
• similarity
• similarly
• simile
• similitude
• simmer
• simmer down
• simmering
• simnel
• simoleon
• simoleons
• Simon
• Simon Bolivar
• Simon de Montfort
• Simon Kuznets
• Simon Legree
• Simon Marks
• Simon Newcomb