Question: Which of the following is a formal definition of proximity? The thieves stopped before they got too close to the bank vault, afraid the proximity alarm would go off. Proximity, which is a noun that means closeness in space or time, is worth a lot of points in Scrabble if you can manage to spell it. Financial planning changes with your proximity to retirement; as retirement nears, you should shift to low-risk investments. Nearness and closeness are synonyms of proximity.