There are multiple definitions:

1. electron transport chain(English)

   • ATP, NADH, ROS, TCA, BCAA, DAG, ECM, ESI, FC, GO, HFpEF, HFrEF, LA, LAVI, MS/MS, RCR, RI, UPLC, ADMA, BODE, CMS, COPD, DLCO, ERA, ET, HAPH, HIF, HPH, HPV, HPVR, mPAP, PASMC, PDE, CMA
   • Physiology, Bioenergetics, Cardiology, Genomics, Oxygen, Adiposity, Frailty, Metabolism
   • https://doi.org/10.1113/JP280572
   • https://doi.org…bts.2021.07.004
   • https://doi.org…1037/atm-22-259
   • https://doi.org….1002/ejhf.3305

2. esophageal tracheal combitube(English)

   • EOA
   • Mouth, esophagus and stomach

3. Ebola treatment center(English)

   • ETU
   • Virology

4. exclusively transcanal [technique](English)

   • ABG, CWD, PORP, TCM, TORP
   • ENT, Surgery
   • https://doi.org…0405-015-3767-6

5. endodontically treated canine(English)

   • Dentistry, Therapeutic approaches
   • https://doi.org…ent.2012.01.002