lightweight
n. countablen. someone who has very little influence or importance in a particular group. In a social setting, it can also describe a person who gets drunk very quickly after only one or two drinks.
n. a person of little importance, influence, or intellectual depth within a specific field. In a colloquial context, refers to an individual with a low tolerance for alcohol.
He is a political lightweight who nobody takes seriously.
The critics dismissed the new director as a lightweight who lacked the vision to handle such a massive budget.
Despite his family's long history in the industry, the heir proved to be a total lightweight, unable to grasp the complexities of international trade law or corporate strategy.
From light (“not heavy”, adjective) + weight (noun).
Often used pejoratively to diminish someone's professional standing.