1.Definition: (slang) someone who has taken a psychedelic drug and is undergoing hallucinations

Category: People

2.Definition: a catch mechanism that acts as a switch

"The pressure activates the tripper and releases the water"

Related Noun(s):trip

Category: Objects

3.Definition: a tourist who is visiting sights of interest

Related Noun(s):excursionist, rubberneck, sightseer

Category: People

4.Definition: a walker or runner who trips and almost falls

Related Noun(s):stumbler

Category: People