be·have / biˈhāv/ • v. [intr.] 1. act or conduct oneself in a specified way, esp. toward others: he always behaved like a gentleman you should behave affectionately toward the patient. ∎  (of a machine or natural phenomenon) work or function in a specified way: each car behaves differently.2. [often in imper.] conduct oneself in accordance with the accepted norms of a society or group: you can go as long as you behave (behave oneself) they were expected to behave themselves.

behave XV. orig. refl., lit. hold oneself in a certain respect; f. BE- + HAVE.
Hence behaviour XV.