the inside track
inner; inside; within
【医】 end-; endo-; ento-; in-; intra-
circle; enclose; fold; loop; mark with circle; pen; ring
【计】 ring up
【化】 circle; enclose; loop; ring
【医】 band; circle; circulus; helico-; ring
racetrack; runway; track
【机】 runway