/ ˈspekjuleɪt; NAmE / verb
1.
speculate (about / on sth) to form an opinion about sth without knowing all the details or facts :
[ v ]
We all speculated about the reasons for her resignation.
[ v wh- ]
It is useless to speculate why he did it.
[ v that ]
We can speculate that the stone circles were used in some sort of pagan ceremony.
2.
[ v ] speculate (in / on sth) to buy goods, property, shares, etc., hoping to make a profit when you sell them, but with the risk of losing money :
He likes to speculate on the stock market.
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WORD ORIGIN
late 16th cent.: from Latin speculat- observed from a vantage point, from the verb speculari , from specula watchtower, from specere to look.