natural family planning

Từ điển WordNet v3.1 - WordNet Dictionary

noun

any of several methods of family planning that do not involve sterilization or contraceptive devices or drugs;
coitus is avoided during the fertile time of a woman's menstrual cycle
• Hypernyms:
birth control, birth prevention, family planning
• Hyponyms:
basal body temperature method of family planning, basal body temperature method, ovulation method of family planning, ovulation method, rhythm method of birth control,
rhythm method, rhythm, calendar method of birth control, calendar method