shoulder peak
n.— «Different rates would be charged electric power users during “super peak hours,” “shoulder peak hours,” and “off peak hours.”» —“Electricity Rates Must Be Stabilized” Herald-Times-Reporter (Manitowoc-Two Rivers, Wis.) Feb. 27, 1976. (source: Double-Tongued Dictionary)
Further reading
What if, instead of being an inanimate object, a dictionary were alive? That’s the idea behind a lavishly illustrated new children’s book called The Dictionary Story (Bookshop|Amazon) by Oliver Jeffers and Sam Winston. This is part of a...