1)
а) обдумывать, взвешивать; размышлять (on, upon, as to, about)

There's little point in speculating about the result of the election when any victory will be very narrow. — Нет смысла делать предположения о результатах выборов, так как любой кандидат может победить лишь небольшим преимуществом голосов.

Syn: think , meditate

б) полагать, предполагать; допускать to speculate that an agreement will be reached — предполагать, что соглашение будет достигнуто Syn: suppose

2) спекулировать; играть на бирже

to speculate for the fall, to speculate for the decline — играть на понижение to speculate for the rise, to speculate for the advance — играть на повышение

en. - Speculate [verb]:

1 [intransitive and transitive] to guess about the possible causes or effects of something, without knowing all the facts or details:
She refused to speculate.
speculate on/about (why/what etc)
Jones refused to speculate about what might happen.
speculate that
Some analysts speculated that jobs will be lost.
2 [intransitive] to buy goods, property, shares in a company etc, hoping that you will make a large profit when you sell them
speculate in/on
He speculated in stocks.