Synonyms for Suffocate (same or very similar meaning)
WordNet sense 1 (deprive of oxygen and prevent from breathing):
asphyxiate, smotherWordNet sense 2 (impair the respiration of or obstruct the air passage of):
choke, stifleWordNet sense 3 (struggle for breath; have insufficient oxygen intake):
gag, strangleFrom the ODE community, based on WordNetadd/edit