There are multiple definitions:

1. power density function(English)

   • also PDF
   • CDF
   • Signal analysis

2. portable document format(English)

   • also denoted as PDF
   • EPS
   • Data exchange, Communication
   • https://doi.org…OC.2022.3154399

3. probability density function(English)

   • a function whose value at any given sample (or point) in the sample space (the set of possible values taken by the random variable) can be interpreted as providing a relative likelihood that the value of the random variable would equal that sample
   • Statistics
   • https://en.wiki…ensity_function
   • https://doi.org…OC.2022.3154399