There are multiple definitions:

1. light emitting diode(English)

   • APD, LD, OLED
   • Bioengineering, Photonics

2. lens equivalent diameter(English)

   • ACD, ACL, LD, LT, LTH, PCI, SS-OCT
   • Ophthalmology
   • https://doi.org…886-021-01884-9

3. levodopa-equivalent dosage(English)

   • ADL, BDI, DBS, GPi, MPTP, STN, UPDRS, UPDRSIII
   • Brain (dys)function, Parkinson
   • https://doi.org…014.4.JNS131711