Saint Sunniva via http://bergen.katolsk.no/?p=5824
Sunniva (SOON-ee-vah) has a beautiful meaning, "sun gift," from its Anglo-Saxon form Sunngifu. It can be found recorded as the variant forms Suniva, Sunneva, Sunnifa, Sunnefa, Syneva, Synna, Synne (which became very popular), Synnev, Synneva, Synneve, Synnevi, Synniva, Synva, and more. The earliest recorded use was Sweden in 1353 but the name is attested to Saint Sunniva from the 10th century, who was an Irish princess. Unfortunately she died from a cave collapsing in Norway after fleeing an invading king who wanted to marry her. Miracles were reported on the little island she escaped to, Selja, with her followers. Her brother became Saint Alban. Their tales were written about in Latin and Icelandic.
This Scandinavian name has been used in Norway (most usage, rank #66 in 2015, also common there in Middle Ages), Sweden, Denmark, Iceland, the Faroe Islands and Finland, hitting the U.S. charts in 2005 with only 5 births. It disappeared until 2011 for no particular reason, and by 2016 was given to 9 girls.
In literature, Sunniva was a character in The Dark Light by Mette Newth. Sunneva Jaarlintytär (Finnish: Sunneva, Daughter of the Jarl) is a novel by Kaari Utrio. There are dozens of real-life namesakes currently for most of the variant spellings.
Sunniva comes with lots of appealing nicknames: Sunny/Sunni, Sun, Suvi, Niva, Eva/Iva, and Sunna.