filler vs synth pad

filler

noun
  • Any spoken sound or word used to fill gaps in speech; filled pause. 

  • Something added to fill a space or add weight or size. 

  • Any semisolid substance used to fill gaps, cracks or pores. 

  • A relatively inert ingredient added to modify physical characteristics. 

  • A short article in a newspaper or magazine. 

  • Any standing tree or standard higher than the surrounding coppice in the form of forest known as "coppice under standards". 

  • material of lower cost or quality that is used to fill a certain television time slot or physical medium, such as a music album 

  • In COBOL, the description of an unnamed part of a record that contains no data relevant to a given context (normally capitalised when in a data division). 

  • One who fills. 

  • A short piece of music or an announcement between radio or TV programmes. 

  • A plant that lacks a distinctive shape and can fill inconvenient spaces around other plants in pots or gardens. 

  • Cut tobacco used to make up the body of a cigar. 

synth pad

noun
  • A sustained chord or tone generated by a synthesizer, often employed for background harmony or atmosphere. 

How often have the words filler and synth pad occurred in a corpus of books? (source: Google Ngram Viewer )