placid
adjective
°calm and quiet; peaceful; tranquil.
"a placid disposition"
incredulity
noun
°Unwillingness or inability to believe; doubt about the truth or verisimilitude of something; disbelief.
°Religious disbelief, lack of faith.
synonyms: incredulousness
conversant
adjective
°closely familiar; current; having frequent interaction.
°familiar or acquainted by use or study; well-informed; versed.