Meaning of decline in English
US /dɪˈklaɪn/ UK /dɪˈklaɪn/
1. a gradual and continuous loss of amount, numbers, quality etc.
The population decline will not stop.
US /dɪˈklaɪn/ UK /dɪˈklaɪn/
1. become less in amount, numbers, quality etc.
decline in popularity
2. politely refuse to accept an invitation, offer, etc.
I'm very sorry to have to declined your invitation.