Plain English Meaning
A small arrow next to the airspeed reading on a glass cockpit display that shows what your airspeed will be in about six seconds if you keep doing what you're doing right now.
Full Definition
A graphical indicator on an electronic airspeed display that shows the predicted airspeed value six seconds into the future, based on the current rate of acceleration or deceleration. It appears as a magenta or cyan arrow extending up or down the airspeed tape from the present airspeed reading.
Context Anchor
Seen on glass cockpit airspeed displays during instrument flying, especially while adjusting pitch or power to hold level flight.
Derivation
Trend' comes from the Old English 'trendan,' meaning to turn or , and now means the direction something is moving. '' comes from the Latin 'vector,' meaning 'carrier' or 'one who conveys,' and in it indicates direction and magnitude. Together: an indicator that shows the direction airspeed is and how fast it's getting there.