What does it mean if two liquids are said to be miscible?

Miscible means that the two liquids will mix in all proportions to form a homogeneous solution so that you can no longer see that there were two liquids (e.g. alcohol and water)

The opposite is immiscible which is where two liquids will not mix together and separate out into two layers (e.g. oil and water are immiscible). Miscible refers to liquids that can be mixed in all proportions. Answers.com