History
History
Synonyms
UK
US
Meaning:
certain

of which there is no possible doubt

confident

collected

(of a person) controlled and not afraid, angry, excited etc

composed, calm

nonchalant

having or showing no interest or enthusiasm

easy-going, laid back

tranquil

calm; quiet

quiet, peaceful

unconcerned

not anxious (about); not (emotionally) concerned (with)

carefree; apathetic

UNPERTURBED as in Wiktionary
UNPERTURBED as in Wikipedia