The Japanese word for one is
一

いち - ichi

Japanese Definition

one
1. 形容詞. ひとつの
2. 形容詞. 一歳の
3. 名詞. 一人。
4. 名詞. 一時・
5. 代名詞. 人
6. 代名詞. それ（前出の単数名詞を指す）

Translations for one and their definitions

人
1. n. a person, human
2. n. an individual
(syn-lite, ja, sc=Jpan, 個人, tr=kojin)
3. n. mankind, people
(syn-lite, ja, sc=Jpan, 人類, tr=jinrui, 人間, tr2=ningen)
4. n. character, personality
(syn-lite, ja, sc=Jpan, 人格, tr=jinkaku, 人柄, tr2=hitogara)
5. n. an average person
(syn-lite, ja, sc=Jpan, 世人, tr=sejin, yohito)
(syn-lite, ja, sc=Jpan, 方, tr=kata, 者, tr2=mono)
6. n. an adult
(syn-lite, ja, sc=Jpan, 大人, tr=otona, 成人, tr2=seijin)
7. n. someone (gloss-lite, else)
8. n. Usage: * When scientifically referring to humans, this term is often spelled in katakana, as (m-lite, ja, sc=Jpan, ヒト).
9. n. Usage: * From (Old Japanese) or w, Middle Japanese development, hito is sometimes shifted to -uto, -udo, -to, -tto, or -do.
10. n. a personality
11. n. the role of that person
12. counter. (n-g-lite, counter for number of people)
13. affix. man
14. suffix. person from that group
アジア人、イギリス人、スペイン人、ドイツ人、アメリカ人、スコットランド人 - an Asian, an Englishman, a Spaniard, a German, an American, a Scot
15. suffix. person who does the activity of the suffixed word
16. suffix. Usage: When compounding, makes the accent fall on the 自立拍 immediately before itself. For example:
17. suffix. Usage: * (m-lite, ja, sc=Jpan, 中国) (m-lite, ja, sc=Jpan, ちゅうごく, ちゅꜜうごく) + m-lite, ja, sc=Jpan, 人 → m-lite, ja, sc=Jpan, 中国人 (m-lite, ja, sc=Jpan, ちゅうごくじん, ちゅうごくꜜじん)
18. suffix. Usage: * (m-lite, ja, sc=Jpan, アメリカ) + m-lite, ja, sc=Jpan, 人 → m-lite, ja, sc=Jpan, アメリカ人 (m-lite, ja, sc=Jpan, アメリカじん, アメリカꜜじん)
19. suffix. Usage: * (m-lite, ja, sc=Jpan, 朝鮮) (m-lite, ja, sc=Jpan, ちょうせん, ちょうせꜜん) + m-lite, ja, sc=Jpan, 人 → m-lite, ja, sc=Jpan, 朝鮮人 (m-lite, ja, sc=Jpan, ちょうせんじん, ちょうせꜜんじん; m-lite, ja, sc=Jpan, ん is a
20. suffix. Usage: * (m-lite, ja, sc=Jpan, スペイン, スペꜜイン) + m-lite, ja, sc=Jpan, 人 → m-lite, ja, sc=Jpan, スペイン人 (m-lite, ja, sc=Jpan, スペインじん, スペイꜜンじん; m-lite, ja, sc=Jpan, ン is a m-lite, ja, sc=Jpan, 特殊拍, tr
21. suffix. Usage: * (m-lite, ja, sc=Jpan, ノルウェー, ノルウェꜜー) + m-lite, ja, sc=Jpan, 人 → ノルウェー人 (m-lite, ja, sc=Jpan, ノルウェーじん, ノルウェꜜーじん; m-lite, ja, sc=Jpan, ー is a m-lite, ja, sc=Jpan, 特殊拍, tr=tokushuh
22. suffix. Usage: There is one notable exception:
23. suffix. Usage: * (m-lite, ja, sc=Jpan, 日本) (m-lite, ja, sc=Jpan, にほん, にほꜜん/m-lite, ja, sc=Jpan, にっぽん, にっぽꜜん) + m-lite, ja, sc=Jpan, 人 → m-lite, ja, sc=Jpan, 日本人 (m-lite, ja, sc=Jpan, にほんじん, にほんじꜜん/m-li
24. affix. man
25. counter. (n-g-lite, counter for number of people)

一
1. Usage: ja-r/multi, data=
2. Usage: * (ja-r/args, linkto=, rom=-, 一, いち) is always omitted before ja-r/args, 十, じゅう, ten and ja-r/args, 百, ひゃく, hundred, but never before the "myriad scale digit names" including ja-r/args
3. Usage: * When before (ja-r/args, 千, せん, thousand), ja-r/args, linkto=, rom=-, 一, いち is omitted when ja-r/args, linkto=, rom=-, 千, せん is not directly followed by ja-r/args, linkto=, rom=-, 万, まん
4. Usage: *: (ja-r/args, 千%百%十%一, せん%ひゃく%じゅう%いち, 1,111)
5. Usage: *: (ja-r/args, 百%万, ひゃく%まん, 1,000,000)
6. Usage: *: (ja-r/args, 一%千%万, いっ%せん%まん, 10,000,000)
7. Usage: *: (ja-r/args, 千%一%万, せん%いち%まん, 10,010,000)
8. n. one, 1
9. n. term relating to the number one:
10. n. the first in order, foremost
11. n. the beginning
12. n. the best
13. n. a kind of; one of something
14. n. (card games) an ace
15. n. unity
16. n. the bottom string of a shamisen or other Japanese musical instrument
17. suffix. the best in …; the most in …
地球の娯楽は宇宙一！ - The entertainments on the earth are the best in the universe!
世界一かわいいよ。 - It's the cutest in the world.
18. affix. one, 1
19. affix. first, foremost
20. affix. once
21. affix. best, number one
22. affix. bunch, bundle
23. affix. entirely, wholly
24. affix. certain one
25. affix. merely, only
26. n. one
27. n. the same
28. affix. one, 1
29. affix. first, foremost
30. affix. group
31. affix. entirely, wholly
32. affix. other
33. affix. merely, only
34. prefix. one, single
35. prefix. all
36. prefix. a bit
37. prefix. a certain time

一つ
1. n. one thing
ブラシを一つ買った。 - I bought a brush.

だれでも
1. conj. 誰でも: anyone

自分
1. n. oneself
過去とは違う自分 - a self who is different from the self of the past
太郎は自分を責めた。 - Taro blamed himself.
2. n. (first-person pronoun): I, me (often shows the speaker's lower position in a hierarchy than the addressee)
3. n. (Kansai) you
4. n. Usage: *

の
1. syllable. (ja-kana-def)
2. part. genitive case marker
3. part. indicates possession: of, -'s
私の意見 - my opinion
4. part. indicates identity or apposition
大統領のブッシュ氏 - the President, Mr. Bush
山田の馬鹿野郎！ - Yamada, you stupid jerk!
山田の奴 - that dude Yamada
5. part. a noun, adverb, or phrase modifier
数学の分野 - the field of mathematics
緑の車 - green car
全ての商品 - all goods
母への手紙 - letter to mom
6. part. nominative case marker in a relative or subordinate clause
眉毛の濃い人 - a man whose eyebrow is thick
7. part. a sentence ending that indicates emphasis or a question, depending on intonation
不可能じゃないの？ - Isn't it impossible?
聞いてんの？ - Are you listening?
8. part. Nominalizes an adjective, verb, or phrase
食べるのが大好きだ。 - I like eating very much.
9. part. (literary) (used with bare i-adjective stem)
懐かしのうた - nostalgic song
麗しの君 - beautiful you
10. part. Usage: * In senses 3 and 4
Usage: * 可能なの? - Is it possible?
Usage: * 色がきれいなのがいい。 - I prefer something with a beautiful color.
11. part. Usage: * For sense 3, use of の in declarative sentences for emphasis carries a female undertone, as compared with
12. part. Usage: * の is sometimes weakened into ん in fixed compounds, such as 桜ん坊 or 飴ん棒.
13. n. 篦: the shaft of an arrow; (arrow bamboo))
14. n. 幅, 布: a unit of measurement for cloth breadth, approximately 36 centimeters