Plural of cloverleaf; highway interchanges shaped like a four-leaf clover that allow traffic to flow in different directions without crossing.
From clover (the plant) + leaf, first used in the early 1900s to describe road interchanges because of their resemblance to a four-leaf clover when viewed from above. The design became popular in the mid-20th century for highway construction.
When engineers designed these road junctions, they literally named them after the lucky plant because the overhead view looks identical to a four-leaf clover! This is a perfect example of how engineers borrow shape names from nature when creating new infrastructure.
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