verbs
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"