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”