Definitions for "Alternate picking"
Every other note is played with a downstroke and every other note is played with an upstroke. Don't cheat, keep it strict
Picking in alternate directions (down-up-down-up).
Alternate picking is a guitar playing technique, necessarily used only by pick users, that employs strictly alternating downward and upward picking strokes in a continuous run, and is the most common method of plectrum playing. If this technique is performed on a single note at a high speed, then it may also be referred to as tremolo picking.