concernyoudaoicibaDictYouDict[concern 词源字典]
concern: [15] In earliest use, English concern meant ‘distinguish, discern’. This was a reflection of its ultimate source, Latin cernere ‘sift, separate’. In combination with the prefix com- ‘together’ it produced concernere, which in classical times meant specifically ‘mix together preparatory to sifting’. Later, however, the prefix seems to have taken on a more intensive role, with concernere reverting to the same range of senses as cernere.

By the Middle Ages these not only included ‘discern, perceive’ and ‘decide’ (whence English certain, from the past participle of cernere), but had widened considerably to ‘relate to’ – a meaning which emerged in English concern in the 16th century. Connotations of distress or worry began to develop in the late 17th century.
=> certain, discern[concern etymology, concern origin, 英语词源]
concern (v.)youdaoicibaDictYouDict
early 15c., "perceive, distinguish," also "refer to, relate to," from Middle French concerner, from Medieval Latin concernere "concern, touch, belong to," figurative use of Late Latin concernere "to sift, mix, as in a sieve," from Latin com- "with" (see com-) + cernere "to sift," hence "perceive, comprehend" (see crisis). Apparently the sense of the prefix shifted to intensive in Medieval Latin. Meaning "worry" is 17c. Related: Concerned; concerning. Letter opening to whom it may concern attested by 1740.
concern (n.)youdaoicibaDictYouDict
1580s, from concern (v.).