What does "ween" mean?

Ween: To think; to imagine; to fancy. [Obs. or Poetic] Spenser. Milton. I have lost more than thou wenest. Chaucer. For well I ween, Never before in the bowers of light Had the form of an earthly fay been seen. J. R. Drake. Though never a dream the roses sent Of science or love's compliment, I ween they smelt as sweet. Mrs. Browning.

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