This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

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n. The blossom of the elderberry, often specifically the European species Sambucus nigra

"A few days later, when I had joined her at her father's house, Jackie and I made a batch of the kind of elderflower cordial/syrup I recently used in a gooseberry relish (see here): equal volumes of water and sugar brought to the boil to form a simple syrup"

elderflower cordial   

calamine    swimmin'    after-shave    Westinghouse    suntan