decline

1 decline /dɪˈklaɪn/ verb
declines; declined; declining
1 decline
/dɪˈklaɪn/
verb
declines; declined; declining
Britannica Dictionary definition of DECLINE
1 
[no object] : to become lower in amount or less in number
2 
[no object] : to become worse in condition or quality
3 
somewhat formal
a  [+ object] : to say that you will not or cannot do something — usually followed by to + verb
b  : to say no to something in a polite way
[+ object]
[no object]
— opposite accept
4 
[+ object] grammar : to list the different forms of (a noun, pronoun, or adjective)

— decliner

/dɪˈklaɪnɚ/ noun, plural decliners [count]

— declining

/dɪˈklaɪnɪŋ/ adjective
2 decline /dɪˈklaɪn/ noun
plural declines
2 decline
/dɪˈklaɪn/
noun
plural declines
Britannica Dictionary definition of DECLINE
1 
: the process of becoming worse in condition or quality
[noncount]
[count]
— usually singular
2 
: a change to a lower number or amount
[count]
[noncount]

on the decline

: becoming worse in condition or less in size, amount, number, etc. : declining