The term "spaced out" can be used to describe a variety of states of mind, ranging from daydreaming to feeling disconnected or confused. There are several alternate expressions that can be used to convey similar meanings. For instance, you can say "lost in thought" to describe someone who is deeply focused on their own thoughts or "zoned out" to describe someone who is not paying attention to their surroundings. If someone is feeling dreamy or unfocused, "in a fog" and "hazy" are also good synonyms for "spaced out". Overall, there is a range of colorful ways to describe the mental state of being "spaced out".