in‧flate /ɪnˈfleɪt/ verb 1 Image of inflate[intransitive, transitive] to fill something with air or gas so it becomes larger, or to become filled with air or gas
It took us half an hour to inflate the dinghy.
Her life jacket failed to inflate.
de‧flate /ˌdiːˈfleɪt, dɪ-/ verb
1 [intransitive, transitive] if a tyre, balloon etc deflates, or if you deflate it, it gets smaller because the gas inside it comes out OPP inflate → go down, let down
In everyday British English, people usually say an object goes down rather than deflates:
It looks like the air bed has gone down.
Look at the picture
What to call a thing such as a balloon or tire that is in the process of losing its air inside it: "the balloon is deflating"?
And this picture
"the balloon is fully inflated"?