verb (used without object)
  1. to make the motions of attack and defense, as in boxing, as a training or conditioning procedure.
  2. to evade or avoid direct or decisive action.

Origin of shadowbox

First recorded in 1915–20; shadow + box2 Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Word Origin and History for shadow boxing

1906; see shadow (n.) + box (v.2). To shadow-box (v.) is attested from 1932. Shadow-fight is attested from 1768; cf. also sciamachy.

Online Etymology Dictionary, © 2010 Douglas Harper