The definition of symbiosis has varied among scientists. Some believe symbiosis should only refer to persistent mutualisms, while others believe it should apply to any type of persistent biological interaction (i.e. mutualistic, commensalistic, or parasitic).
The Golden Pledge, which is a System Plus Warranty with a 20 year leak guarantee, can pay for itself within the first ten years, sometimes many times over. The System Plus transforms the normal warranty by removing the small print.
pledge (third-person singular simple present pledges, present participle pledging, simple past and past participle pledged) 1  To make a solemn promise (to do something). 2  To deposit something as a security; to pawn. ( 3 transitive) To give assurance of friendship by the act of drinking; to drink to one's health.