c. 1400, resumen, "repossess, resume possession" (of goods, money, etc.); early 15c., "regain, take back, take to oneself anew" (courage, strength, hope, etc.); from Old French resumer (14c.) and directly from Latin resumere "take again, take up again, assume again," from re- "again" (denoting "repetition of an action;" see re-) + sumere "to take, obtain, buy," from sus‑, variant of sub‑ "up from under" + emere "to take" (from PIE root *em- "to take, distribute").
From mid-15c. as "recommence, continue (a practice, custom, occupation, etc.), begin again after interruption;" also "begin again." The intransitive sense of "proceed after interruption" is from 1802. Related: Resumed; resuming.
also résumé, 1804, "a summary, summing up, recapitulation," from French résumé, noun use of past participle of resumer "to sum up," from Latin resumere "take again, take up again" (see resume (v.)). Meaning "biographical summary of a person's career" is 1940s.