"Night lettergram" refers to a clandestine form of communication used during the past, whereby secret messages were sent under the cover of darkness. Synonyms for this term are abundant, such as "midnight missive", "evening epistle", or "dusk dispatch". These alternative expressions capture the essence of the secretive nature and time-specific aspect of the original term. Each synonym conveys the idea of clandestine written communication that takes place during the night, adding intrigue and mystery to the act of sending messages under the veil of darkness. Accessing a wide range of synonyms allows for variety and creativity in describing this unique mode of secret communication.