(1):

(v. i.) To fall off from the normal quality or the healthy structure of its kind; to become of a lower type.

(2):

(v. i.) To be or grow worse than one's kind, or than one was originally; hence, to be inferior; to grow poorer, meaner, or more vicious; to decline in good qualities; to deteriorate.

(3):

(a.) Having become worse than one's kind, or one's former state; having declined in worth; having lost in goodness; deteriorated; degraded; unworthy; base; low.