1. The blood group whose red cells lack the Rh factor (Rh antigen)
   - Rh-negative blood, Rh negative

Type of: blood group, blood type

• sigmoidoscopy
• Sigmund Freud
• Sigmund Romberg
• sign
• sign away
• sign in
• sign industry
• sign language
• sign manual
• sign of the cross
• sign of the zodiac
• sign off
• sign on
• sign over
• sign painter
• sign up
• signage
• signal
• signal box
• signal caller
• signal detection
• signal fire
• signal flag
• signal level
• signal light