​Trend Analysis ​of Rainfall and ​Runoff

I am doing a trend analysis of rainfall and runoff using parametric test.

My question is, if I do a regression analysis and find a slope of increase or decrease with a certain value, like 2mm/year, but the trend is non-significant with 90% probability, can it still be called a trend?

If yes, then what is the exact meaning of statistical significance and non-significance?