There are multiple definitions:

1. periodic-acid Schiff(English)

2. persistent angular structure(English)

   • DSI, HARDI

3. physician assisted suicide(English)

   • TS
   • Iatrogenic, Terminal / palliative care, Suicide

4. paired associative stimulation(English)

   • noninvasive brain stimulation technique
   • MEP, TMS
   • Electrophysiology, Physiology, Receptors
   • https://doi.org…CI.3655-13.2014

5. platelet additive solution(English)

   • Hematology

6. placenta accreta spectrum(English)

   • umbrella term for a variety of pregnancy complications due to abnormal placental implantation, including placenta accreta, placenta increta and placenta percreta
   • EVT, PP
   • Pregnancy, Obstetrics
   • https://doi.org…grb.2021.02.001

7. penetration-aspiration scale(English)

   • refers to the evaluation of the deglutitive functions after repair of esophageal atresia and/or tracheoesophageal fistula
   • EA, GERD, TEF, VFS
   • Pediatrics, Mouth, esophagus and stomach, Scoring systems/scales, Respiratory system
   • https://doi.org…urg.2015.07.002

8. Per[iod]-Arnt-Sim(English)

   • bHLH, EPAS1, LIPG
   • Molecular biology, Circadian rhythm, Depression, Transcription
   • https://doi.org…jpet.104.068692
   • https://doi.org…science.1190371
   • https://doi.org…jmb.2023.168370

9. pancreas allocation system(English)

   • should lessen the declining pancreas transplant numbers
   • PAK, PTA, SPK, SPT
   • Pancreas, Transplantation
   • https://doi.org…000000000000146

10. preclinical Alzheimer's disease scale(English)

    • AD, CSF, MCI
    • Alzheimer's disease, Scoring systems/scales
    • https://doi.org…554790490896785

11. prosthetic aortic stenosis(English)

    • AVR, GLS, AS
    • Cardiology, Prosthetics, Medical imaging
    • https://doi.org…GING.116.005942

12. posterior-to-anterior stiffness(English)

    • refers to a new thoracic spine training simulator
    • HAM, FSTT, SP, TP
    • Spine (or spinal cord), Exercise & Training
    • https://doi.org….7899/JCE-19-14

13. peripheral anterior synechiae(English)

    • APAC, IOP, LPI
    • Ophthalmology
    • https://doi.org…tha.2004.01.036

14. peripheral anionic site(English)

    • AChE, CAS
    • Enzymes
    • https://doi.org…02.2022.2162583

15. patient access scheme(English)

    • one way in which pharmaceutical companies can lower the acquisition cost of a medicine to the NHS, enabling patients to gain access to high cost medicine treatments. Sometimes referred to as risk share scheme or market access scheme
    • ERG, KSR, LEN, NHS, NICE, STA
    • Pharmacology / pharmaceutics, Economics and health care, Patient care, Financial issues, Health insurance, Health care industry
    • https://doi.org…0273-017-0581-6
    • https://www.lpp…access schemes.

16. phagophore assembly site(English)

    • a perivacuolar site
    • AMP, AMPK, BARS, ER, BIF-1, LC3, mTOR, PI, ULK1, UVRAG, Vps34
    • https://doi.org/10.1002/rmv.1973

17. para-aortic splanchnopleura(English)

    • AGM
    • Transcription
    • https://doi.org…9822(99)80368-6

18. para amino salicylic [acid](English)

    • refers to the low therapeutic index for certain second-line drugs
    • AFB, API, ATT, DOTS, HCC, IUATLD, MDR, NNRTI, SCC, TB, WHO, HIV
    • Microbiology, Pulmonology
    • http://pubmed.n…h.gov/16800350/