What does 'intelligent money' mean? Is 'intelligent money' or 'smart money' an economic term, and if yes, what does it refer to?
"Intelligent money" or "smart money" is not an economic term per se, but a finance term.

It is colloquially used in the finance industry to describe the collective group of individuals who are paid to actively manage funds, rather than passively manage funds. Active management differs from passive management in that the former chooses how to invest money based on individual perceptions of expected return, whereas the latter follows a predetermined simple rule, such as "buy equities in a weighting equal to their individual market valuations amongst the largest x stocks". 

More generally, 'smart money' refers to the subset of active managers that act as if they possessed an informational advantage, and/or the ability to adapt a fund's investment strategy to market conditions. In this sense, smart money consists of hedge funds and stock-picking mutual funds and 'dumb money' consists of passive mutual funds. (Passive funds are more likely to be ETFs, though it's not mutually exclusive).

However few economists would consider investing with active managers to be the intelligent choice (given equal risk, passive investment outperforms active investment on average, net of fees).

Since the term is colloquial, it is hard to find an example which provides a definition. Notwithstanding this, the following article's title lines up with this explanation, and further, explains why "smart money" isn't ordinarily a smart place for money.

http://time.com/money/3657009/indexing-investing-inflows-vanguard-blackrock/