1. Concave on both sides
   - biconcave

See also: concave

• stereotypic
• stereotypical
• stereotypically
• stereotypy
• steric
• sterile
• sterileness
• sterilisation
• sterilise
• sterilised
• steriliser
• sterility
• sterilization
• sterilize
• sterilized
• sterilizer
• sterlet
• sterling
• sterling area
• sterling bloc
• sterling silver
• stern
• stern chaser
• Sterna
• Sterna hirundo