The antonyms of "becoming visible" are disappearing, hiding, vanishing, concealing, and masking. These words refer to the process or action of not being seen or hidden from view. For instance, when something disappears, it is no longer visible, while hiding indicates an intentional act of being out of sight. Vanishing suggests a sudden disappearance, and concealing refers to the act of covering or keeping hidden from view. Similarly, masking involves the use of a device or covering to prevent something from being visible. The antonyms of becoming visible, therefore, denote the opposite state of being unseen or concealed.