Bertrun is a name of German origin, meaning a bright secret rune.
Bertrun is a compound name. Its parts are rún — each an attested element with a recorded meaning of its own.
Bertrun 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 Bertrun reduce to 8, The Visionary. This is a traditional interpretive system, not a factual claim about the name.