What is the meaning of speculation?

noun

• A message expressing an opinion based on incomplete evidence.
  • synonyms: guess, conjecture, supposition, surmise, surmisal, hypothesis
• A hypothesis that has been formed by speculating or conjecturing (usually with little hard evidence. )
  • usage: "speculations about the outcome of the election"; "he dismissed it as mere conjecture"
  • synonyms: conjecture
• An investment that is very risky but could yield great profits.
  • usage: "he knew the stock was a speculation when he bought it"
  • synonyms: venture
• Continuous and profound contemplation or musing on a subject or series of subjects of a deep or abstruse nature.
  • usage: "the habit of meditation is the basis for all real knowledge"
  • synonyms: meditation