Wariness is the feeling of not fully trusting something, so you stay careful and keep watching. It is the noun that goes with wary. It is not fear — fear makes you run, wariness makes you slow down and look again. It is also not shyness. A person full of wariness may talk to you happily; they simply do not hand over their trust yet. You will often see it about people and about ideas: "a wariness of strangers", "public wariness about the new law", "he treated the offer with wariness". Notice the small words that follow it: wariness of somebody, or wariness about something. Because it names a feeling, it is normally uncountable — you say "her wariness", not "a wariness" (though writers sometimes do say "a certain wariness", which is fine). It often turns up when someone has been hurt before: past experience leaves wariness behind. That is a useful clue to its meaning — wariness usually has a history.