thoughtless vs unproper

thoughtless

adj
  • Inconsiderate, inattentive. 

  • Lacking thought or consideration. 

  • Marked by or showing lack of due thought or care; careless. 

unproper

adj
  • Improper, not according with good standards of behaviour; indecent, indecorous. 

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