a cover: a place or condition of being hidden, whether for shelter or for secrecy
At its root this word names a covering, something that screens a person or thing from view. Everything it does grows out of that single picture. A cloth or a curtain hides; a ridge or a thicket hides; the dark hides; and so the word can name the physical thing that covers, the safe place you take cover in, or the simple fact that something is out of sight.
Two very different feelings sit inside that one idea, and the Hebrew Bible plays on both. To be hidden can mean to be safe, sheltered behind something stronger than the danger, which is why this is one of Scripture's favorite words for refuge in God. But to be hidden can also mean to be unseen by witnesses, free to act in the dark, which is why it is just as readily the word for a thing done in secret, a slander muttered low, an idol set up where no one can see.
So the senses below are not separate words but one word seen from different sides: the cover itself, the shelter it gives, and the secrecy it allows. The same darkness that protects can also conceal wrongdoing, and the Bible lets the word carry both without explaining the tension away.