rh

Everyday

1. Rh (rhesus) factor: a protein that may be on red blood cells; blood is Rh-positive or Rh-negative (as in A+ or O−). tree →
2. RH: short for «right hand», as in music («RH» for the right hand on the piano). tree →
3. RH or rh: short for «relative humidity», how much water vapour is in the air. tree →
4. Rh: the chemical symbol for rhodium, a rare metal. tree →

In the lessons

In science and health lessons blood groups have a letter (A, B, AB, O) and a plus or minus sign for Rh. Doctors check Rh before blood transfusions and in pregnancy. In piano music RH and LH tell you which hand plays. Not a word you say; read the letters «R-H» or the full word.

Examples

• My blood group is O, Rh positive. tree →
• Rh-negative blood is less common. tree →
• In piano music, RH means play with your right hand. tree →
• The weather station shows RH 80%. tree →
• Rh is the symbol for the metal rhodium. tree →

Note

An abbreviation, not a word. Say «R-H» or «rhesus». The meaning depends on the subject.