The term 'be mischievous' can be broken down into five crossword solutions: ARCH (4 letters), IMPISH (6 letters), IMPS (4 letters), ELFIN (5 letters), and ELF (3 letters). The word ARCH is an adjective meaning clever or cunning, while IMPISH is an adjective meaning mischievous or naughty. IMPS are small, mischievous creatures from folklore, while ELFIN is an adjective meaning small and delicate, and ELF is a noun referring to a supernatural creature from folklore. All of these words together suggest that the phrase 'be mischievous' means to act in a playful, naughty, or cunning manner.