inflation is the sustained increase in the general price level of goods and services in an economy over a period of time.

it comes from 'inflare' which is latin meaning to blow up.

in terms of bitcoin prices have blown up in the last 3 years. everything is 100% more expensive measured in bitcoin than 3 years ago.
today bitcoin buys only 50% of the same house it bought 3 years ago.
everything became more expensive measured in bitcoin