From Longman Dictionary of Contemporary Englishflexflex1 /fleks/ verb [transitive] 1 BENDto tighten your muscles or bend part of your body2 → flex your muscles→ See Verb table
Examples from the Corpus
flex• The former is the inability to extend the knee completely when the thigh is flexed.• I just hoped that all that flexing and twisting of the hull would not burst the 3,000 rattan lashings.• She watched him raise one hand to rub the nape of his neck, then flex his shoulder muscles.• The arms of the dead warrior seemed to flex, moved by heat, twisted by the consuming flame.• She let blood in, and flexed the fingers.• Lying as shown, flex the foot and swing the top leg forwards and backwards 5 times.• The raft had to flex to survive, but there was a serious penalty: the constant movement produced tremendous abrasion.flexflex2 noun [countable] British English HPETan electrical wire covered with plastic, used to connect electrical equipment to an electricity supply SYN cord American English → leadExamples from the Corpus
flex• It's safe but you need to have a firm grip to cut a 13-amp flex.• The single framed print hanging on the wall on the first landing, the dead lightbulbs suspended pointlessly from their dusty flexes.• For the younger and fitter elderly person, though, the long flex is a very good idea.• Six amp three-core mains flex is used for the mains input which connects straight to the p.c.b.• The prosecution alleges Hammond attacked the girl with his hands, fists, a ruler and the flex from an electric kettle.• Suddenly Donald was tied to his chair with the flex from the lamp, the plug still attached.Origin flex (1500-1600) Latin flexus; → FLEXIBLE flex2 (1900-2000) flexible 