The compound "Thursday-night" is a modern English formation that combines the specific day "Thursday" with the general time period "night". "Thursday" itself has a rich mythological history, originating from the Old English "Day of Thunor (Thor)", the god associated with thunder, strength, and protection. "Night" is an ancient, fundamental concept tracing back to a common Proto-Indo-European root. When combined, these two morphemes create a precise temporal marker, moving from the mythological naming of a day to the practical designation of a specific evening within the weekly cycle. The logic is straightforwardly compositional, specifying which night of the week is being referenced.

Structure: thursday (day of the week) + night (period of darkness) - thursday: From Old English Þūnresdæg, meaning "day of Thunor (Thor)". Thunor was the Old English name for the Norse god of thunder, equivalent to the Roman god Jove/Jupiter. The name is a compound of the god's name and dæg (day). - night: From Old English niht, meaning "the period of darkness between sunset and sunrise". It originates from Proto-Germanic \nahts, which in turn derives from the Proto-Indo-European root \nekwt-, meaning "night".