flex

Universal Words verb, noun verb to bend, move or stretch an arm or leg, or tighten a muscle, especially in order to prepare for a physical activity: [VN] to flex your fingers / feet / legs * He stood on the side of the pool flexing his muscles. [also V] IDIOMS flex your muscles to show sb how powerful you are, especially as a warning or a threat noun (BrE) (also cord AmE, BrE) [C,U] a piece of wire that is covered with plastic, used for carrying electricity to a piece of equipment: an electric flex * a length of flex