What is the definition of transparent clothing in Islamic jurisprudence, and is clothing that shows the outlines of the undergarments without revealing skin color considered transparent, and what is the ruling on praying in it?

Transparent clothing is that which does not conceal the skin beneath it. The ruling on prayer in such clothing is a matter of disagreement, with three main opinions: that prayer must be repeated absolutely, or that it is valid absolutely, or a detailed view differentiating between what reveals the 'awrah upon close inspection and what does not. The conclusion is that prayer is valid with clothing as long as it conceals the 'awrah and does not show the color of the skin. The transparency of the outer garment (jilbab) is not an issue if there is something underneath it that conceals the 'awrah.