Unprotected means having no defence or covering. Exposed, and nothing between you and whatever is coming.
It describes places, people and equipment, so an unprotected coastline, unprotected workers and unprotected wiring are all standard. Health uses it in a specific and important sense about sex without contraception. Computing uses it for data left without security. The word always implies that protection was possible and is absent, which is what makes it a warning rather than a description.
1adjectiveunprotectedHaving no covering, defence or safeguard.
“The cables had been left unprotected.”
From un- + protected.
Etymology from Wiktionary, CC BY-SA