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Webster 1913 Edition

Adj.

[L.

Cassis

helmet.]

(Bot.)

Helmet-shaped; – applied to a corolla having a broad, helmet-shaped upper petal, as in aconite.

cassideous ‎(comparative more cassideous, superlative most cassideous)

(botany) Shaped like a helmet; applied to a corolla with a broad, helmet-shaped upper petal, as in aconite.