What does "swine" mean?

Swine: Swine grass (Bot.), knotgrass (Polygonum aviculare); -- so called because eaten by swine. -- Swine oat (Bot.), a kind of oat sometimes grown for swine. -- Swine's cress (Bot.), a species of cress of the genus Senebiera (S. Coronopus). -- Swine's head, a dolt; a blockhead. [Obs.] Chaucer. -- Swine thistle (Bot.), the sow thistle.

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