((n.) A small, dry, indehiscent fruit, containing a single
seed, as in the buttercup; -- called a naked seed by the earlier
botanists.)
Origin:
Early 19th century; earliest use found in John Lindley (1799–1865), botanist and horticulturist. From scientific Latin achaenium from ancient Greek ἀ- + χαίνειν to gape + scientific Latin -ium.