The term 'causing ennui' can be described by four words found in a crossword puzzle: BORE (4 letters), TEDIUM (6 letters), BORED (5 letters), and BLAHS (5 letters), and YAWN (4 letters). BORE is a verb meaning to cause someone to feel tired or uninterested, while TEDIUM is a noun meaning a state of weariness and dissatisfaction. BORED is an adjective describing a feeling of being tired and uninterested, and BLAHS is another word for ennui, which is a feeling of listlessness and dissatisfaction. Finally, YAWN is a verb meaning to open one's mouth wide and take a deep breath due to tiredness or boredom. All of these words describe the feeling of ennui, which is a feeling of listlessness and dissatisfaction.