initial vs lead-in

initial

noun
  • A distinguished initial letter of a chapter or section of a document. 

  • onset, part of a syllable that precedes the syllable nucleus in phonetics and phonology. 

  • The first letter of a word or a name. 

  • In plural, the first letter of each word of a person's full name considered as a unit. 

verb
  • To sign one's initial(s), as an abbreviated signature. 

adj
  • Spatially first, placed at the beginning, in the first position; especially said of the first letter of a word. 

  • Chronologically first, early; of or pertaining to the beginning, cause or origin. 

lead-in

noun
  • An introduction; something that leads into the beginning of something. 

  • A short phrase that begins the caption of a photograph. 

  • A region of data at the beginning of a compact disc, holding the table of contents. 

How often have the words initial and lead-in occurred in a corpus of books? (source: Google Ngram Viewer )