soporific

Từ điển Oxford Advanced Learner 8th

sop·or·if·ic BrE [ˌsɒpəˈrɪfɪk] NAmE [ˌsɑːpəˈrɪfɪk] adjective (formal)
making you want to go to sleep
•the soporific effect of the sun

Word Origin:
[soporific] mid 17th cent.: from Latin sopor ‘sleep’ -ific.

• Từ đồng nghĩa / Synonyms:
  narcotic, soporiferous, somniferous, somnific, hypnogogic, hypnagogic, hypnotic