one, 1 / the first in order, foremost / the beginning / the best / a kind of; one of something / (card games) an ace / unity / the bottom string of a shamisen or other Japanese musical instrument

necessary evil

necessity (quality or state of being necessary, unavoidable, or absolutely requisite)

unnecessary

needlessness

each person

Alternative form of 一々

first, foremost, number one

one person

one person / singleness, singularity / one's own efforts or strengths / an unmarried person, single