Synonyms for Stifling (same or very similar meaning)
WordNet sense 1 (characterized by oppressive heat and humidity):
sulfurous, sultry, sulphurous
WordNet sense 2 (used of physical heat; having a high or higher than desirable temperature or giving off heat or feeling or causing a sensation of heat or burning):
hot
WordNet sense 3 (forceful prevention; putting down by power or authority):
crushing, suppression, quelling
From the ODE community, based on WordNet
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