This is the 1898th most frequent Japanese word.
純
"純" means "pure" or "genuine."
The word "純粋な" (jun sei na) is derived from "純" (jun), meaning pure or unmixed, and is used here as an adjective to describe the purity of her heart.
彼女の純粋な心は誰にでも感じ取れる。
Her pure heart can be felt by anyone.
The term "純度" (jun do), combining "純" (jun) with "度" (do, degree), indicates the degree of purity of the cacao.
このチョコレートは純度99%のカカオを使用している。
This chocolate uses 99% pure cacao.
The phrase "純利益" (jun rieki) incorporates "純" (jun), implying 'net' or 'pure' in the financial context, paired with "利益" (rieki, profit).