1) Big 2) Direction 
• (p. pr. & vb. n.) of Trend
Methods of estimating future costs of health services by reviewing past trends in cost and utilization of these services. Also see Actuarial. 
Trending is a term used in charting. It is a price which is moving up or down and includes temporary reversals of the main trend.
A word, phrase or topic that is popular on Twitter at a given moment.