奔

Top 大 - pictograph of a person standing front-on with arms spread wide. The indexing radical here, supplying the figure that does the running. The image of a person flung forward, arms outstretched, is exactly the running posture 奔 names: not a jog but a full-tilt sprint.

Bottom 卉 - three blades of grass clustered together, originally drawn as feet moving through vegetation. Under the running figure above it gives the compound ideograph reading: a person tearing through tall grass at a sprint. The grassy-ground sense supplies the speed and urgency that distinguish 奔 from ordinary 走 walking.