Idil is from the Somali Idil — complete, perfect, whole (also Turkish-Tatar İdil — Volga River). Idil is one of the Somali feminine names — central to traditional Somali pastoral + Sunni Muslim heritage.
Idil 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 Idil reduce to 7, The Seeker. This is a traditional interpretive system, not a factual claim about the name.