"Don't sweat it" was a slang expression in the 1950s that meant "not to worry."
"50 slang" could refer to slang from the 1950s (such as "cool cat" or "greaser") or slang that originated in the area code 50 in Minnesota. More context would be needed to provide a specific answer.
Some teenage slang from the 1950s included phrases like "cool it," "cruisin' for a bruisin'," "pad," "threads," and "hot rod." These terms were often used by young people to express approval, warn of potential trouble, refer to a hangout spot, describe clothing, or talk about a fast car.
"Cool" is a slang word! It means popular or faddish.
Some African American slang words from the 1950s include "cool" (meaning stylish or impressive), "dig" (understand or appreciate), and "jive" (deceptive or exaggerated talk). These terms were commonly used within the jazz and blues communities.
A popular slang term for leaving in the 1950s was "split," as in "Let's split this joint."
Cool itself, unless you are using it to mean mildly cold, is a slang word. Just because it is old slang doesn't mean that it is not still slang.
Yes
In the 1950s, slang terms like "cool" (meaning fashionable or stylish), "daddy-o" (a term for a fashionable or cool person), and "beatnik" (referring to a person associated with the Beat Generation) were popular. Additionally, phrases like "Pad" (a place where someone lives or hangs out) and "groovy" (meaning excellent or fashionable) were commonly used.
This word "Slang" is an abbreviation of "Sick Language" i.e. SLANG. and in slang "Sick" means "Cool".
"Cat" in slang means: female, person or friend. So, "Cool Cat" would just mean a cool person.
cool