plank
n. countable B2 Upper Intermediate US //ˈpɫæŋk// UK //plˈæŋk// plank
n. a long, flat piece of wood used for building. If you call someone this, you mean they are very stupid or slow to understand.
n. a long, thin, flat piece of timber used in construction. In British English, it serves as a mild pejorative for a person perceived as unintelligent or foolish.
He used a thick plank to repair the garden fence.
The carpenter carefully measured each plank before cutting it to fit the new floor frame.
The political platform was built upon a central plank of tax reform, which the candidate argued would stimulate growth across the manufacturing sector.
Usage
When used as a pejorative, it is informal and primarily found in British English.