zero period
n.— «The new schedule has seven 50-minute periods, and extends the school day by 15 minutes. Before, the high school day had six 55-minute periods, but many students took an extra class —- commonly called a “zero period”—before the regular day began.» —“High school reform arrives” by Carolyn Norton Herald-Sun (Durham, North Carolina) Aug. 23, 2006. (source: Double-Tongued Dictionary)
Further reading
Some college students are using the word loyalty as a synonym for monogamy. Are the meanings of these words now shifting? Plus, a biologist discovers a new species of bat, then names it after a poet he admires. Also, warm memories of how a childhood...
A North Carolina listener is curious about his meemaw’s use of a term meaning “food” that he heard as either jasmine or jassum. A dialectal term with various spellings that include jassum, jasum, and jazm can mean “gravy,” “sauce,” or even “juice...