Almost all of you have heard of the word Mâyâ. Generally it is used, though incorrectly, to denote illusion, or delusion, or some such thing. But the theory of Maya forms one of the pillars upon which the Vedanta rests; it is, therefore, necessary that it should be properly understood. I ask a little patience of you, for there is a great danger of its being misunderstood.
The oldest idea of Maya that we find in Vedic literature is the sense of delusion; but then the real theory had not been reached. We find such passages as, “Indra through his Maya assumed various forms.” Here it is true the word Maya means something like magic, and we find various other passages, always taking the same meaning
Source: Maya and illusion