Inflation is the increase in prices of services and commodities. From a different standpoint inflation can be interpreted as decrease in the value of money.
In a cashless society services and commodities are exchanged for other commodities and services(barter system). So any change in the exchange rate of these services can be viewed as increase in value of one commodity or services and decrease in the value of another. So this can be interpreted as inflation with respect to a commodity and deflation with respect to another commodity.Alternatively in a cashless society services and commodities can be exchanged for a common commodity such as gold. In this case gold can be viewed as a currency and any increase in prices relative to gold can be viewed as inflation.