indefinite vs some kind of

indefinite

noun
  • A word or phrase that designates an unspecified or unidentified person or thing or group of persons or things. 

adj
  • Undecided or uncertain. 

  • Being an integral without specified limits. 

  • Vague or unclear. 

  • Designating an unspecified or unidentified person or thing or group of persons or things 

  • Without limit; forever, or until further notice; not definite. 

some kind of

det
  • A remarkable. 

  • a mediocre; a bare minimum; (denoting that something only barely fits a certain category, or is very mediocre in it) 

  • Used other than figuratively or idiomatically: see some, kind, of. 

adv
  • Used as an intensifier of adjectives: remarkably 

How often have the words indefinite and some kind of occurred in a corpus of books? (source: Google Ngram Viewer )