commensal (n.)youdaoicibaDictYouDict[commensal 词源字典]
"one who eats at the same table" (as another), c. 1400, from Old French commensal (15c.), from Medieval Latin commensalis, from com- "together" (see com-) + mensa (genitive mensalis) "table" (see mesa). Biological sense attested from 1870.[commensal etymology, commensal origin, 英语词源]