1.a: Capable of being bent or flexed; pliable: a flexible hose.
1.b: Readily bending or twisting the body without injury: You can play soccer much better if you’re flexible.
2. Able to change to cope with variable circumstances: “a flexible and quietly competent administrator” (Jerome Karabel).
3. Capable of being changed or adjusted to meet particular or varied needs: a job with flexible hours; a flexible definition of normality.