What does Waist Overalls mean?

The initial term used for what are now known as jeans.

Heddels explains Waist Overalls

Now an antiquated phrase, waist overalls was the original term Jacob Davis and Levi Strauss used when they began selling their riveted denim pants in 1873. Levi’s continued to be known as waist overalls until the 1960s, when the term “jeans” was finally adopted.

Additional Resources

Here is an example of waist overalls: