The term 'Hours of Darkness' refers to the period of time during the NIGHT when it is dark outside. The crossword solution for this term is 'NIGHT, ' which is a five-letter word. NIGHT is the period of time between sunset and sunrise when it is dark outside. During this time, the sun is below the horizon and the sky is usually clear of clouds. Nighttime is typically associated with rest and relaxation, as well as activities such as stargazing and nocturnal wildlife watching.