flexion
noun
flex·ion ˈflek-shən 
1
: the act of flexing or bending
2
: a part bent : bend
3
: inflection sense 2
4
a
: a bending movement around a joint in a limb (such as the knee or elbow) that decreases the angle between the bones of the limb at the joint compare extension sense 3b
b
: a forward raising of the arm or leg by a movement at the shoulder or hip joint
Example Sentences
Recent Examples on the Web Use wrist flexion to unroll the string until the weight nearly touches the ground. 
Jen Murphy, WSJ, 3 Sep. 2022 Exercises that don’t include lots of knee flexion include deadlift variations, glute bridges, and hip thrusts, which are primarily centered on movement at the hip joint versus the knee joint. Jenny Mccoy, SELF, 13 Aug. 2022 The side plank is the most obvious example of an anti-lateral flexion movement, but it’s certainly not the only one. Men's Health, 22 Aug. 2022 The combination of the hip extension, knee flexion (when your knee is bent), and the location of the load at your hips likely plays a vital role in its high glute activation. Tiffany Ayuda, SELF, 12 Aug. 2022 If the side bend worked as intended, Samuel says the move would train anti-lateral flexion (similar to a side plank). Jeff Tomko, Men's Health, 10 Aug. 2022 That might be more appropriate for some because the curl-up doesn't challenge the hip flexion power, which is so important in athleticism, whereas the single arm and the opposite leg lift just has the opposite hand under the low back. Greg Presto, Men's Health, 14 July 2022 The intensity of the repeats should first focus on strong form and technique with your head up, arms parallel (think hip to nip), and strong hip and knee flexion and extension. Lukus Klawitter, Outside Online, 27 July 2020 Flex one foot upward, hold for five seconds, and then instead of moving from flexion to extension immediately, continue the flex, leading with the ball of your foot reaching forward. Stephanie Mansour, CNN, 9 June 2022 See More
Jen Murphy, WSJ, 3 Sep. 2022 Exercises that don’t include lots of knee flexion include deadlift variations, glute bridges, and hip thrusts, which are primarily centered on movement at the hip joint versus the knee joint. Jenny Mccoy, SELF, 13 Aug. 2022 The side plank is the most obvious example of an anti-lateral flexion movement, but it’s certainly not the only one. Men's Health, 22 Aug. 2022 The combination of the hip extension, knee flexion (when your knee is bent), and the location of the load at your hips likely plays a vital role in its high glute activation. Tiffany Ayuda, SELF, 12 Aug. 2022 If the side bend worked as intended, Samuel says the move would train anti-lateral flexion (similar to a side plank). Jeff Tomko, Men's Health, 10 Aug. 2022 That might be more appropriate for some because the curl-up doesn't challenge the hip flexion power, which is so important in athleticism, whereas the single arm and the opposite leg lift just has the opposite hand under the low back. Greg Presto, Men's Health, 14 July 2022 The intensity of the repeats should first focus on strong form and technique with your head up, arms parallel (think hip to nip), and strong hip and knee flexion and extension. Lukus Klawitter, Outside Online, 27 July 2020 Flex one foot upward, hold for five seconds, and then instead of moving from flexion to extension immediately, continue the flex, leading with the ball of your foot reaching forward. Stephanie Mansour, CNN, 9 June 2022 See More Word History
Etymology
borrowed from Latin flexiōn-, flexiō "act of bending or curving," from flectere "to cause to go in a different direction, bend, curve" (of uncertain origin) + -tiōn-, -tiō, suffix of verbal action
First Known Use
1615, in the meaning defined at sense 1
Medical Definition
flexion
noun
flex·ion
variants also flection
ˈflek-shən
1
: a bending movement around a joint in a limb (as the knee or elbow) that decreases the angle between the bones of the limb at the joint compare extension sense 2
2
: a forward raising of the arm or leg by a movement at the shoulder or hip joint