• Webster's Revised Unabridged Dictionary
    • n Buttonweed (Bot) The name of several plants of the genera Spermacoce and Diodia, of the Madder family.
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Century Dictionary and Cyclopedia
    • n buttonweed A name given to several rubiaceous plants belonging to the genera Spermacoce, Diodia, and Borreria.
    • n buttonweed The knapweed, Centaurea nigra.
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