What's the "entropy" amount in de wallet-overview on tronscan.org?

I created a testwallet on tronscan.org and played a little bit with it. Sent some TRX, froze some and requested 100k trx. Everything went perfectly fine!! BTW: sending TRX to another wallet was instantly done. No wait-time! In my wallet overview i see my TRX value, the amount of frozen TRX and a value named "Entropy". Does anybody know what this is? Thanks!