| ic | between meals [Lat. inter cibos] |
|---|---|
| ICR | [distance between] iliac crests; Institute for Cancer Research; Institute for Cancer Research [mouse... |
| ISP | distance between iliac spines; interspace; intraspinal; isoproterenol |
| MTBF | mean time between (or before) failures |
| P-R | the time between the P wave and the beginning of the QRS complex in electrocardiography [interval] |