Definitions
1.NounAn individual or corporation that intends to acquire another company in order to avert a hostile takeover.
2.NounA hero, savior, or righteous individual.
3.NounSomeone who unnecessarily defends someone else.
A man who defends a woman in debate etc. in an attempt to gain her favour.
4.NounA man who defends a woman in debate etc. in an attempt to gain her favour.
5.NounA mushroom of species Tricholoma album.
6.NounUsed other than figuratively or idiomatically: see white, knight."The white knight is attacking the pawn on e4."
7.VerbTo unnecessarily defend someone, especially in an attempt to gain favour.