The term 12 MONTHS can be solved by the crossword solution YEAR, which is a four-letter word. Year is a unit of time that is commonly used to measure the duration of a period of time. It is typically divided into twelve months, each of which has either 28, 30, or 31 days. The Gregorian calendar is the most widely used calendar system in the world today and it is based on a solar cycle of 365 days, with an extra day added every fourth year.