Henriikka

I am a Finnish woman with this as my middle name. My father had a grandmother named Fredrika (called Reetriikka because she was Savonian), and they then looked up names similar to that and finally found, and settled on, Henriikka. That combined with my first name is actually rather unique and I don't think there's anyone in Finland with the same combination.

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Though personally, I've never really liked Henriikka all that much. I find it to be a very old-fashioned name, kind of like a verbal manifestation of a dusty attic.... Though there's a pro to having it as a middle name - it's very rare.