Dictionary

To reach a partly (or totally) unqualified conclusion.

To solve by a correct conjecture; to conjecture rightly.

Example: He who guesses the riddle shall have the ring.

To suppose (introducing a proposition of uncertain plausibility).

Example: That album is quite hard to find, but I guess you could try ordering it online.

To think, conclude, or decide (without a connotation of uncertainty). Usually in first person: "I guess".

Example: "I guess I'll go to bed."

A prediction about the outcome of something, typically made without factual evidence or support.

Example: If you don't know the answer, take a guess.