The correct spelling is Questionnaire. It must contain a double ‘n’ followed by ‘aire’, which is a common point of error for many learners.

১. Questionaire (single n) is incorrect as the word is derived from the French structure requiring a double consonant.
২. Questionair and Questionoir are phonetic misspellings that do not exist in standard English.
৩. This noun refers to a list of questions used to gather information from people.

অতিরিক্ত তথ্য: The word originated from the late 19th-century French word ‘questionnaire’.