"Waaniyaa" (وانیا) is not a word with any meaning. However, "Waaniyah" (وَانِیَہ) is an Arabic word meaning lazy, weak, and frail in body. Since these meanings are unfavourable, parents should instead name their daughter after one of the Sahabiyat, or choose another purposeful and meaningful name.
Allah the Almighty knows best.
Darul Ifta Al-Ikhlas, Karachi.
القاموس الوحید: (ص: 1902، ط: ادارۃ اسلامیات)
الوانی:
1.سست، کمزور۔
2.لاغر جسم۔