Answer: slipperiest

AnswerCrossword Clue
slipperiestSLIPPERY, tending to cause slipping
slipperiest(of a person) Evasive and unpredictable; not to be relied on
slipperiest(of a surface or object) Difficult to hold firmly or stand on because it is smooth, wet, or slimy
slipperiest(of a word or concept) Elusive in meaning because changing according to one's point of view