IPA: /nɒnˈʃæl.əns/
KK: /nɑnˈʃɑlən(t)s/
A relaxed and calm attitude, showing little or no concern about something.
His nonchalance during the meeting surprised everyone, as they expected him to be more worried.
Nonchalance → It is formed from "non-" (meaning not) and "chalance" (from French *chalance*, meaning to be at ease or relaxed). The word describes a state of being not concerned or relaxed, indicating a lack of interest or enthusiasm.
Think of 'not' ('non-') being relaxed or at ease ('chalance') — this helps you remember that nonchalance means a lack of concern or indifference.
No commonly confused words.