(1):

(n.) A pledge, bond, or other security for the performance of an obligation either in or out of judicial proceedings; the promise or contract of one not for himself but another; security.

(2):

(n.) Precept or warning against evil of any kind; exhortation to wariness; advice; injunction.

(3):

(n.) A careful attention to the probable effects of an act, in order that failure or harm may be avoided; prudence in regard to danger; provident care; wariness.

(4):

(v. t.) To give notice of danger to; to warn; to exhort [one] to take heed.

(5):

(n.) Security; guaranty; bail.