Brief Calm is a term used to describe a period of time in which there is a lack of activity or disruption. It is often used to describe a moment of peace and tranquility, such as a LULL in a conversation or a pause in a storm. The crossword solution for this term is LULL, which is a four-letter word meaning to become quiet or still. This term is often used to describe a period of rest or relaxation, and can also be used to refer to a period of sleep.