Finnish word kaunis comes from Proto-Indo-European *(s)kewh₁-, Proto-Indo-European *(s)ḱoun-, Proto-Indo-European *(s)ḱown-, and later Proto-Germanic *skauniz (Beautiful, shining.)

Detailed word origin of kaunis

Dictionary entry	Language	Definition
*(s)kewh₁-	Proto-Indo-European (ine-pro)
*(s)ḱoun-	Proto-Indo-European (ine-pro)	quick, dashing, beautiful
*(s)ḱown-	Proto-Indo-European (ine-pro)
*skauniz	Proto-Germanic (gem-pro)	Beautiful, shining.
kaunis	Finnish (fin)	Beautiful.