It is an adjective.
Meaning: It means argumentative.It is used to refer to the complaining or grumbling nature of a person.It is a negative word.It is used to indicate when someone is inclined to hurt other person with words and make them feel embarrassed.
Etymology: From Latin word - 'querulus' meaning 'to complain'
Root of the word : quer/ques/quis/quire = question
Synonyms : complaining, peevish, fretful, fretting, tetchy, censorious, disagreeable, irritable,whiny,carping.
Antonyms : agreeable,contented
querulously - adverb
querulousness - noun
1)The querulous journalist kept on bombarding his objections to the new scheme during the press conference.
2)I never heard a querulous tone from him.
3)I wanted to stay for some more time but the querulous voice insisted to leave.
4)Criticism though helps to know our mistakes and improve but it should not be querulous.