num·ber one inf. • n. 1. oneself: you must look after number one. 2. a person or thing that is the best or the most important in an activity or area: businesses that were number one in their markets. ∎ a best-selling record or book: an album featuring seventeen top movie themes and six number ones. 3. used euphemistically to refer to urine, esp. in reference to children. 4. a lieutenant junior grade in the navy or the coast guard. 5. (or number two, etc.) the shortest (or next shortest, etc.) men's haircut produced with electric hair clippers. • adj. most important or prevalent: a number-one priority. ∎ best selling: a number-one album.
"number one." The Oxford Pocket Dictionary of Current English. . Encyclopedia.com. (September 20, 2018). http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/number-one
"number one." The Oxford Pocket Dictionary of Current English. . Retrieved September 20, 2018 from Encyclopedia.com: http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/number-one