speculator

Etymology

From Latin speculātor (“spy, explorer, investigator”), from speculor (“to watch, to observe”) + -tor (“-er: forming agent nouns”), from specula (“watchtower”), from speciō (“to watch, to observe”), q.v. In some senses, an agent noun formed within English from speculate. Doublet of spectator.

noun

1. One who speculates; an observer; a contemplator.
   a bold and paradoxical speculator
2. One who forms theories; a theorist.
   […] in things of Fact, the People are as much to be believed, as the most subtle Philosophers and Speculators, since here sense is the Judge. 1666, Joseph Glanvill, Philosophical Considerations concerning Witches and Witchcraft
   For, in the earlier part of the seventeenth century, a speculator who had dared to affirm that the human soul is by its nature mortal, and does, in the great majority of cases, actually die with the body, would have been burned alive in Smithfield. 1848, Thomas Babington Macaulay, The History of England from the Accession of James the Second
3. (business, finance) One who speculates; as in investing, one who is willing to take volatile risks upon invested principal for the potential of substantial returns.
4. (rugby) Synonym of field goal