1. Flat on one side and convex on the other

See also: bulging, convex

• X factor
• x-axis
• X-linked
• X-linked dominant inheritance
• X-linked gene
• X-linked recessive inheritance
• X-linked SCID
• X-OR circuit
• X-radiation
• X-rated
• x-ray
• X-ray astronomy
• X-ray crystallography
• X-ray diffraction
• X-ray film
• X-ray machine
• X-ray photograph
• X-ray photography
• X-ray picture
• X-ray therapy
• X-ray tube
• X-raying
• X-SCID
• Xanadu
• Xanax