v.intr. 1 (usu. foll. by with) a (of a person) meddle; obstruct a process etc. b (of a thing) be a hindrance; get in the way. 2 (usu. foll. by in) take part or intervene, esp. without invitation or necessity. 3 (foll. by with) euphem. molest or assault sexually. 4 Physics (of light or other waves) combine so as to cause interference. 5 (of a horse) knock one leg against another. interferer n. interfering adj. interferingly adv.
[ OF s' entreferir strike each other (as INTER-, ferir f. L ferire strike) ]