speculate

/ˈspe-kyə-ˌlāt/

Latin speculatus, past participle of speculari to spy out, examine, from specula lookout post, from specere to look, look at

verb

to meditate on or ponder a subject : reflect
to review something idly or casually and often inconclusively
to assume a business risk in hope of gain; especially : to make a relatively risky investment in something (such as stocks or real estate) in the hope of making a large short-term profit from market fluctuations

think cogitate reflect reason speculate deliberate mean to use one's powers of conception, judgment, or inference. think is general and may apply to any mental activity, but used alone often suggests attainment of clear ideas or conclusions. cogitate implies deep or intent thinking.