Karuna (करुणा) is the Sanskrit-Pali word for "compassion" — one of the four Brahmavihārās (sublime states) of Buddhism, alongside loving-kindness, sympathetic joy, and equanimity. The compassion of Avalokiteshvara (Guanyin) is named for her.
Used widely across South and East Asia.
Karuna does not currently appear in the US Social Security Administration's top 1,000 girls' names, so we don't publish a US rank or birth count for it. That says nothing about the name's standing elsewhere in the world — only that it sits outside the ranked US data we rely on.
In Pythagorean numerology the letters of Karuna reduce to 3, The Communicator. This is a traditional interpretive system, not a factual claim about the name.