The term 'solstice month' refers to the month in which the solstice occurs. In the Northern Hemisphere, the solstice month is JUNE, which is represented by the four-letter answer to the crossword puzzle. The solstice is an astronomical event that marks the longest and shortest days of the year, when the sun reaches its highest or lowest point in the sky. During the summer solstice, which occurs in JUNE in the Northern Hemisphere, the sun is at its highest point in the sky and the day is the longest of the year.