antieffective 

The opposite of effective.

Despite good intentions, the new drug was antieffective, and killed all participants in the initial trial.

antieffective by dactylo November 2, 2010

antiffective 

(adjective) possessing the quality of reducing the ability of others to accomplish a purpose; reducing the efficacy of others' intended or expected results; not merely ineffective, but actively reducing the efficiency of others.

The way that he drags the rest of the team backwards on this project is totally antiffective.

antiffective by star_boy_oz May 14, 2015

andeffective 

A mealy-mouthed "feature" of some hyped product, spoken after cheerful and virtuous-sounding words like "safe" or cheap", and intended to not actually lie but sometimes to trick someone into thinking you mean one thing when you may actually mean something entirely the opposite.

When a radio or TV advertiser says that some medicine or other edible substance is "tasty andeffective", I never know if he is indeed saying, "and effective", or if he's really saying, "and DEfective"!

andeffective by QuacksO December 8, 2016