Decline

verb (used with object), declined, declining.
1.
to withhold or deny consent to do, enter into or upon, etc.; refuse:
He declined to say more about it.
2.
to express inability or reluctance to accept; refuse with courtesy:
to decline an invitation; to decline an offer.
3.
to cause to slope or incline downward.
4.
Grammar.

to inflect (a noun, pronoun, or adjective), as Latin puella, declined puella, puellae, puellae, puellam, puella in the five cases of the singular.
to recite or display all or some subset of the inflected forms of a noun, pronoun, or adjective in a fixed order.

verb (used without object), declined, declining.
5.
to express courteous refusal; refuse:
We sent him an invitation but he declined.
6.
to bend or slant down; slope downward; descend:
The hill declines to the lake.
7.
(of pathways, routes, objects, etc.) to follow a downward course or path:
The sun declined in the skies.
8.
to draw toward the close, as the day.
9.
to fail in strength, vigor, character, value, etc.; deteriorate.
10.
to fail or dwindle; sink or fade away:
to decline in popularity.
11.
to descend, as to an unworthy level; stoop.
12.
Grammar. to be characterized by declension.
noun
13.
a downward slope; declivity.
14.
a downward movement, as of prices or population; diminution:
a decline in the stock market.
15.
a failing or gradual loss, as in strength, character, power, or value; deterioration:
the decline of the Roman Empire.
16.
a gradual deterioration of the physical powers, as in later life or in disease:
After his seventieth birthday he went into a decline.
17.
progress downward or toward the close, as of the sun or the day.
18.
the later years or last part:
He became an editor in the decline of his life.
verb
1.
to refuse to do or accept (something), esp politely
2.
(intransitive) to grow smaller; diminish: demand has declined over the years
3.
to slope or cause to slope downwards
4.
(intransitive) to deteriorate gradually, as in quality, health, or character
5.
(grammar) to state or list the inflections of (a noun, adjective, or pronoun), or (of a noun, adjective, or pronoun) to be inflected for number, case, or gender Compare conjugate (sense 1)
noun
6.
gradual deterioration or loss
7.
a movement downwards or towards something smaller; diminution
8.
a downward slope; declivity
9.
(archaic) any slowly progressive disease, such as tuberculosis