| PTB | patellar tendon bearing; prior to birth |
|---|---|
| PTR | patellar tendon reflex; patient termination record; patient to return; peripheral total resistance; ... |
| ACN | acute conditioned neurosis; Ambulatory Care Network; American College of Neuropsychiatrists; America... |
| ANN | artificial neural network |
| ARPANET | Advanced Research Projects Agency Network |