There are multiple definitions:

1. periodic-acid Schiff(English)

   • stains neutral and acid simple nonsulfated and acid complex sulfated mucins, and also various inclusions, bodies, granules and secretions composed of mucopolysaccharides or mucins
   • Microscopy, Pathology, Histochemistry
   • https://doi.org….1111/vcp.70076

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/

19. Pregnancy Anxiety Scale(English)

    • a clinical tool used to identify and measure anxiety symptoms in pregnant women, helping differentiate mild from severe anxiety to guide treatment, with scoring ranges indicating severity (e.g., 0-20 minimal, 21-41 mild-moderate, 42-93 severe) and a cutoff of 26 suggesting higher risk. Often referring to the Perinatal Anxiety Screening Scale (PASS)
    • APS, BDI, BSI, CCI, CES-DS, DSSI, EPDS, EPL, JCQ, LEBI, LESPW, PASS, PESI, POQ, PRAQ, PSAT, PSQ, PSS, RSI, SLEQ, STAI, SVAWS
    • Pregnancy, Anxiety/fear, Scoring systems/scales
    • https://pubmed.…ih.gov/1765627/
    • https://pubmed.…h.gov/30328596/

20. pulmonary artery sarcoma(English)

    • an extremely rare, aggressive cancer of the pulmonary artery wall, often mistaken for blood clots (pulmonary embolism) due to similar symptoms (cough, chest pain, shortness of breath) and imaging, leading to significant diagnostic delays and poor prognosis. Diagnosis relies on advanced imaging (PET/CT) and biopsy
    • AS, BP, COG, CTRCD, DFS, ECG, GIST, ICI, LMS, LVEF, PCS, RMS, STS, TKI, UPS
    • Vascular disease, Oncology, Pulmonology, Medical imaging, Biopsy, Diagnostics
    • https://doi.org…cao.2025.09.005

21. pulmonary artery stiffness(English)

    • identified as an independent risk factor for RV dysfunction and it is elevated in HFpEF
    • HFpEF, RVEF, RVEF/PAS
    • Vascular disease, Pulmonology, Hemodynamics, Echography/ultrasound, Risk factor, Screening
    • https://doi.org…1111/echo.70385

22. Physical Ability Score(English)

    • patients with ischemic left ventricular dysfunction and poor exercise capacity have increased early risk and similar 5-year mortality with CABG compared with medical therapy, whereas those with better exercise capacity have improved survival with CABG
    • CABG, LVD, STICH
    • Scoring systems/scales, Cardiology, Pathology, Exercise & Training, Questionnaire, Fatigue, Prognosis
    • https://doi.org…chf.2014.02.009