Tilly is the English diminutive of Matilda — from the Germanic maht (might) and hild (battle) — meaning "mighty in battle."
Tilly is rising as part of the broader vintage diminutive revival. Tilly is the AI character in the Pixar/Disney film Ratatouille, and various young actresses bear the name.
Tilly 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 Tilly reduce to 6, The Nurturer. This is a traditional interpretive system, not a factual claim about the name.