"Personnel" refers to people employed in an organisation or engaged in an organised undertaking such as military service. e.g.
"Many of the personnel involved require training". Its synonyms are staff, employees. workforce, workers, labour force etc.
Personnels also means an administrative division of an organization concerned with the body of persons employed by or active in it and often acting as a liaison between different departments.
It is wrong to refer to a person as personnel. Personnel is already plural; you don't need the "s".
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