Other forms: flexed, flexing, flexes
To flex is to bend and tighten a joint or a muscle, testing that it still moves. Fingers, a knee, a shoulder after sleeping on it.
Bodybuilding gave us flexing a muscle to display it, and from that comes the modern informal noun, since a flex is a show of wealth or status and flexing is the act of it. British English also uses flex as a noun for an electrical lead. The adjective flexible means both able to bend and willing to adapt, and flexibility is prized in both senses.
1verbflexTo bend and tighten a muscle or joint.
“He would flex his fingers before starting to play.”
2nounelectricalAn electrical lead.
“The flex on the kettle has frayed.”
Flex is a bend. Latin flectō meant to bend, which is why a lead that bends where a cable will not is called a flex.
Latin
flexus
English, today
flex
Built from
From Latin flexus, past participle of flecto (“to bend”).
Etymology from Wiktionary, CC BY-SA