[Medieval Latin prōpulsiō, prōpulsiōn-, onslaught, urging on, from Latin prōpulsus, past participle of prōpellere, to drive forward; see propel.] pro·pul'sive, pro·pul'so·ry (-sə-rē) adj.
1611, "expulsion," noun of action formed from pp. stem of L. propellere "to propel" (see propel). Meaning "act of driving forward" first attested 1799.