- flux [ flʌks ] noun1. ) uncount a condition of continuous change:in a state of flux: The climate appears to be in a state of flux.in flux: The committee's ideas were still in flux.2. ) count or uncount SCIENCE the rate at which matter or energy flows across a surface or area3. ) uncount TECHNICAL a substance used for joining two pieces of metal together
Usage of the words and phrases in modern English. 2013.