Something that is not heavy.

Light as in illumination.

रोशनी

English Usage: The room needs more light to be bright.

Hindi Usage: कमरे में रोशनी और चाहिए ताकि यह उजाला रहे।

Evidence or argument establishing a fact.

साक्ष्य

English Usage: The proof of his innocence was overwhelming.

Hindi Usage: उसकी निर्दोषता का साक्ष्य अविश्वसनीय था।

Not dark; bright.

उजाला

English Usage: The light colors make the room feel larger.

Hindi Usage: हल्के रंग कमरे को बड़ा महसूस कराते हैं।

Designed to resist something; impervious.

रोधक

English Usage: These shoes are waterproof, so they can be used in the rain.

Hindi Usage: ये जूते waterproof हैं, इसलिए इन्हें बारिश में इस्तेमाल किया जा सकता है।