Trudy is the English diminutive of Gertrude — from the Old Germanic gar (spear) + thrudh (strength). Trudy Ederle (1905-2003) — born Gertrude Caroline Ederle in Manhattan — on August 6, 1926, at age 19, became the first woman to swim across the English Channel; she completed the 21-mile crossing in 14 hours 31 minutes, more than 2 hours faster than any of the five men who had done it before her. She had won three Olympic medals at Paris 1924 at age 17; she swam the Channel partially deaf from a childhood case of measles, and was nearly completely deaf by middle age. Honored by Calvin Coolidge as "America's best girl."
Trudy 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 Trudy reduce to 7, The Seeker. This is a traditional interpretive system, not a factual claim about the name.