deflated, coward, wimp, flat
Je suis un dégonflé, par rapport à toi.
I'm a wimp compared to you.
Tu t'attendais à un matelas dégonflé ?
Were you expecting a deflated mattress?
— The Big Sick (2017)
The tire is a little deflated.
Tom a dû pousser sa bicyclette aujourd'hui car il avait un pneu dégonflé.
Tom had to push his bicycle today because he had a flat tire.