index finger vs palp

index finger

noun

  • the forefinger 

palp

noun

  • A fleshy part of a fingertip. 

  • Synonym of pedipalp. 

adj

  • Palpatory; obtained by palpation. 

verb

  • To feel, to explore by touch. 

How often have the words index finger and palp occurred in a corpus of books? (source: Google Ngram Viewer )