Plectrude is a name of Old Germanic origin, meaning frankish queen (pippin's widow).
Plectrude is a compound name. Its parts are þrúðr — each an attested element with a recorded meaning of its own.
Plectrude 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 Plectrude reduce to 5, The Seeker. This is a traditional interpretive system, not a factual claim about the name.