Black moon is a name recently (2016) [1] given to various new moons or absences of them, within a year. It is not a term used in astronomy and there is no single accepted definition of it.[2] Among the meanings ascribed to it are these: a second new moon that appears in the same month; the third new moon in an astronomical season with four new moons; the absence of a new moon in February; or the absence of a full moon in February.[2]
timeanddate
was invoked but never defined (see the help page).