noun which may take the genitive case particle 'no', noun
Indicates the first in a sequence, rank, or order. Often used with の to modify nouns.
彼はクラスで第一の成績を取った。
He got the top grades in the class.
第一印象はとても
First impressions are very important.
noun which may take the genitive case particle 'no', noun
most important; best; foremost
Emphasizes priority or supreme importance. Overlaps with sense 1 but focuses on qualitative primacy rather than numerical order.
健康が第一だ。
Health is the most important thing.
安全を第一に考えてください。
Please put safety first.
adverb
first of all; to begin with; above all
Adverbial use, often at the start of a sentence or clause, to introduce a primary reason or point. Can also imply 'in the first place' or 'anyway'.
第一、お金がないから旅行には行けない。
To begin with, I can't go on a trip because I don't have money.
第一、彼はまだ子供だ。
First of all, he's still a child.