A Rubber by Any Other Name is Still a Rubber

Sexually transmitted infections[edit]

U.S. propaganda poster Fool the Axis Use Prophylaxis, 1942

Sexually transmitted infections (STIs), such as syphilis and HIV, are common but preventable with safe-sex practices. STIs can be asymptomatic, or cause a range of symptoms. Preventive measures for STIs are called prophylactics. The term especially applies to the use of condoms,^[45] which are highly effective at preventing disease,^[46] but also to other devices meant to prevent STIs,^[45] such as dental dams and latex gloves. Other means for preventing STIs include education on how to use condoms or other such barrier devices, testing partners before having unprotected sex, receiving regular STI screenings, to both receive treatment and prevent spreading STIs to partners, and, specifically for HIV, regularly taking prophylactic antiretroviral drugs, such as Truvada. Post-exposure prophylaxis, started within 72 hours (optimally less than 1 hour) after exposure to high-risk fluids, can also protect against HIV transmission.

Preventive healthcare - Wikipedia

Apparently, prophylactic or prophylaxis can mean any number of methods used to prevent disease including, but not limited to, rubbers.  According to Wiki, Uncle Ken is correct about rubbers being around long before they began making them out of rubber.  Obviously, then, they couldn't have been called "rubbers" in those days of old when nights were bold, but I doubt that they were called "condoms" either.  I just can't picture Sir Lancelot explaining to his lady fair that, before he can tend to her needs, he first must slay yon sheep so that he can make a condom out of its guts.