OA meaning in Space Science ?

Overalls, also called bib-and-brace overalls or dungarees, are a type of garment usually used as protective clothing when working. The garments are commonly referred to as a "pair of overalls" by analogy with "pair of trousers".

Overalls were originally made of denim, but they can also be made of corduroy or chino cloth. Overalls were invented in the 1890s by Levi Strauss and Jacob W. Davis at Levi Strauss & Co., but they went through an evolution to reach their modern form. Initially only used for protective clothing in work settings, they have become a garment of high fashion as "potential cult items". Overalls have been trending recently and have been prevalent in streetwear. Many high fashion brands have released their own spin on overalls.