Today's word is "nonchalant".
This is an adjective which means coolly unconcerned.
For example, you can say, "His nonchalant nature was very
frustrating to her; he just didn't seem to care what she
Türkçe Karşılığı :
s. kayıtsız, ilgisiz, lakayt, soğukkanlı, heyecansız