In a heart-shaped manner; in a way that is cordate or resembles a heart.
From the adjective cordate combined with the adverbial suffix -ly. This creates an uncommon but grammatically proper way to describe something being done in a heart-shaped fashion.
This is a botanist's adverb—almost never used in everyday speech, it exists in technical literature to describe how leaves are arranged or how they appear to unfold in a heart-shaped way.
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