a form containing a set of questions; submitted to people to gain statistical information
"The market research team distributed a questionnaire to customers to gather data on their purchasing habits."
A form containing a list of questions; a means of gathering information for a survey
"The researcher distributed a questionnaire to gather data on customer satisfaction."
"The teacher asked everyone to fill out a short questionnaire about their weekend activities."
Usage: A questionnaire is a written or digital form used to collect data from respondents, distinct from an interview which involves direct verbal interaction. You can also use the verb "questionnaire" when describing the act of conducting such surveys on a group.
to survey using questionnaires
"The marketing team decided to survey their customers by distributing a questionnaire via email."
In plain English: To questionnaire someone is to ask them questions on purpose, though this verb form is rarely used and people usually just say they are questioning or surveying others instead.
"The teacher questioned every student about their homework answers."
The word questionnaire comes from the French term of the same name, which was derived from Late Latin. It originally combined a root meaning "to ask" with a suffix indicating an agent or instrument, effectively describing something designed to gather answers through questions.