decline

Concise Oxford English Dictionary © 2008 Oxford University Press:
decline/dɪˈklʌɪn/

▶verb

• 1 become smaller, fewer, or less; decrease.

  ■ diminish in strength or quality; deteriorate.

• 2 politely refuse: the company declined to comment.

• 3 (especially of the sun) move downwards.

• 4 Grammar state the forms of (a noun, pronoun, or adjective) corresponding to cases, number, and gender.

▶noun

• 1 a continuous loss of strength, numbers, or value.

• 2 archaic a disease in which the bodily strength gradually fails, especially tuberculosis.

– derivatives
declinable adjective,
decliner noun,
declining adjective.

– origin ME: from OFr. decliner, from L. declinare ‘bend down, turn aside’, from de- ‘down’ + clinare ‘to bend’.