achenium

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• n. achene

from The Century Dictionary and Cyclopedia

• n. In botany, a small, dry and hard, one-celled, one-seeded, indehiscent fruit; strictly, a single and free carpel of this character, as in the buttercup, avens, etc., but extended to all similar fruits resulting from a compound ovary, even when invested with an adnate calyx, as in the order Compositæ. Also written achene, achænium, akene, and akenium.
• n. In entomology, a genus of beetles.