There is a law in physics named "The law of entropy increasing". It says that whatever you do, whatever you say, the entropy (the disorder) in this world increases. For example: I sweep in my home with a broom, I make more disorder outside my home when I throw the trash.
This is what happens with the money in the world, no matter what I am doing (deleting the zeros from some paper money, making 100 000 000 whatever money to be 100 new money, etc) the total money in this world increases. With the total money, the prices increase. In my country in the last 10 years, the prices have increased approx 7 times, while the salaries increased 1.5 times.
A deflationary currency is a currency that makes the prices to increase slower than the salaries. That is, a person can afford to go travel to other countries, can feed himself and his family very good, can buy 3 homes, etc. In this understanding bitcoin is a deflationary currency. It allows the earnings (the reward of a person work) to grow faster than the prices.
In physics, the entropy is indeed increasing globally, but under extreme circumstances it's possible to decrease it locally, forming a new kind of order, at the expense of the global increase. And financial inflation can be compared with entropy in a sense that devaluation is like disorder, but I don't think the example holds till the end. Deflation means that the value of money is growing rather than going down. 1 BTC now is less than 1 BTC in a year kind of thing. The prices, however, can get adjusted in various ways. Deflation is widely considered to be a bad thing because it does not encourage people to spend money (why buy something now if I can buy more of it in a week?), but this view supposes that people are behaving rationally when making purchase decisions, which they aren't.
