careless vs unguarded

careless

adj
  • Not giving sufficient attention or thought, especially concerning the avoidance of harm or mistakes. 

  • Not concerned or worried (about). 

unguarded

adj
  • Displaying a lack of caution or thought. 

  • Having no guard or protection; vulnerable. 

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