[L. incompatibilis]

1. The quality of not being suitable for mixture. It can be applied to a state that renders admixture of medicines unsuitable through chemical action or interaction, insolubility, formation of poisonous or explosive compounds, difference in solubility, or antagonistic action.
2. The quality of not being mixed without chemical changes, or without countering the action of other ingredients in a compound.
3. The condition of not being in harmony with one's surroundings or associates, esp. a spouse or friend.
Blood Type Compatibility

Compatibility with Recipient Blood Type
Donor Blood TypeType A BloodType B BloodType AB BloodType O Blood

ABO incompatibility

An antigen-antibody immune response to infusion of another's red blood cells. Transfusion reactions occur most commonly in people with type O blood, which carries no antigens on the red blood cells and contains both anti-A and anti-B antibodies. People with type A blood carry A antigens on their red cells and anti-B antibodies; those with type B blood carry B antigens and anti-A antibodies; those with type AB blood carry both A and B antigens but no antibodies to A or B. The antibodies are called natural antibodies because their formation does not require sensitization by A and B antigens. The antibodies recognize the antigens on the donor cells as foreign and destroy them by agglutination and lysis. ABO incompatibilities are different from Rh incompatibilities, which are most commonly related to the D antigen in the Rh blood group. SEE TABLE: Blood Type Compatibility; SEE: blood group
Obstetrics: Transplacental fetal-maternal transfusion occurs when fetal blood cells escape into the maternal circulation, eliciting antibody formation. Maternal antibodies then cross the placenta into the fetal circulation, attack, and destroy red blood cells, as evidenced by neonatal hyperbilirubinemia and jaundice.

physiological incompatibility

A condition in which one or more substances in a mixture oppose or counteract one of the other compounds being administered.