v. 1 intr. (usu. foll. by on, upon, about) form a theory or conjecture, esp. without a firm factual basis; meditate (speculated on their prospects). 2 tr. (foll. by that, how, etc. + clause) conjecture, consider (speculated how he might achieve it). 3 intr. a invest in stocks etc. in the hope of gain but with the possibility of loss. b gamble recklessly. speculator n.
[ L speculari spy out, observe f. specula watch-tower f. specere look ]