speculator

One that speculates.

An observer or onlooker; a watcher; a lookout; a seer; in a specific use, an occult seer; one who looks into mysteries or secrete by magical means.

One who engages in mental speculation; a person who speculates about a subject or subjects; a theorizer.

One who practises speculation in trade or business of any kind. See speculation, 4.

One who speculates. Specifically: (a) An observer; a contemplator; hence, a spy; a watcher.