The adjective "vialed" typically means covered or concealed by a veil. Some synonyms for "vialed" include "shrouded," "veiled," "concealed," "hidden," "masked," and "obscured." These words all suggest something that is not easily visible or readily apparent. Additional synonyms could include "camouflaged," "disguised," or "cloaked," which all imply a deliberate attempt to conceal something from view. In different contexts, other words may be more appropriate. For example, if talking about a person behaving shyly or reservedly, you may use "reticent" or "withdrawn" as synonyms. The specific synonym you choose will depend on the nuances of the situation and the writer's intent.