Cough

咳

seki

(sudden, often involuntary expulsion of air from the lungs through the glottis, and out through the mouth)

咳をする

seki o suru

(to push air from the lungs through the glottis (causing a short, explosive sound) and out through the mouth)

咳払いをする

sekibarai o suru

(to make a noise like a cough)