asphyxiate

deprive of oxygen and prevent from breathing; "Othello smothered Desdemona with a pillow"; "The child suffocated herself with a plastic bag that the parents had left on the floor"

impair the respiration of or obstruct the air passage of; "The foul air was slowly suffocating the children"

be asphyxiated; die from lack of oxygen; "The child suffocated under the pillow"