Lidija is the Croatian/Serbian form of Lydia — from the Greek Lydía (referring to ancient Lydia in western Anatolia). Lidija Šentjurc — Slovenian historical figure. Lidija Andrijić — Serbian artist. Lidija Vukićević — Serbian actress. Lidija Krčmar — Croatian academic. Lidija Manić — modern Serbian-American figure. Princess Lidija — modern South Slavic heritage naming.
Lidija 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 Lidija reduce to 9, The Giver. This is a traditional interpretive system, not a factual claim about the name.