What is the meaning of Flex?

Flexibility, pliancy.

An act of flexing.

Any flexible insulated electrical wiring.

A flexible insulated electrical cord.

Flexible ductwork, typically flexible plastic over a metal wire coil to shape a tube.

A point of inflection.

An act or instance of flaunting something; a boast or brag; something considered impressive.

To bend something.

To repeatedly bend one of one's joints.

To move part of the body using one's muscles.

To tighten the muscles for display of size or strength.

To boast or brag about; to flaunt (something).

To flaunt one's superiority; to show off.

angle grinder

flex (an act or instance of flaunting something; a boast or brag; something considered impressive)

Alternative form of flax

Alternative form of fleax

to flaunt, to show off, in an either positive or negative manner

Source: wiktionary.org