信: letter; to trust; sincerity

信 xìn

noun | adjective
: letter; mail
: to trust; to believe; to profess faith in
: sincerity; truthful; confidence; trust; at will; at random

信じる OR 信ずる |
しんじる shinjiru OR しんずる shinzuru

ichidan verb | zuru verb | transitive verb
: to believe; to believe in; to place trust in; to confide in; to have faith in

誠 OR 実 | まこと makoto

adverb | noun
: truth; reality;
: sincerity; honesty; integrity; fidelity;
: (Archaism) that’s right (used when recalling forgotten information, suddenly changing the subject, etc.)

信封 xin4feng1: envelope

信心 xin4xin1: confidence; faith (in somebody or something)
[しんじん shinjin: faith; belief; devotion; godliness]

信箱 xin4xiang1: mailbox

信念 xin4 nian4: faith; belief; conviction
[しんねん shinnen: belief; faith; conviction]

信息 xin4xi1: information; news; message

信任 xin4ren4: to trust; to have confidence in
[しんにん shinnin: trust; confidence; credence]

信用 xin4yong4: to trust; credit (commerce); trustworthiness; creditworthiness
[しんよう shinyou: confidence; dependence; credit; faith; reliance; belief; credence; trust]

不信用 bu4 xin4 yong4: distrust; discredit [ふしんよう fushinyou]  
守信用 shou3 xin4 yong4: to keep one’s word; trustworthy

信義[义] xin4yi4: good faith; honor; trust and justice
[信義 | しんぎ shingi: faith; fidelity; loyalty]

相信 xiang1xin4: to be convinced (that something is true); to believe; to accept something as true

來[来]信 lai2xin4: incoming letter; send a letter here
[来信 | らいしん raishin: letter received]

回信 hui2xin4: to reply; to write back; letter written in reply

寫[写]信 xie3xin4: to write a letter

忠信 zhong1xin4: faithful and honest; loyal and sincere
[ちゅうしん chuushin: faithfulness; devotion]

通信 tong1xin4: to correspond (by letter etc); to communicate; communication
[つうしん tsuushin: correspondence; communication; transmission; news; signal]

短信 duan3 xin4: text message; SMS
[たんしん tanshin: brief note or letter; brief message]

發[发]短信 fa1 duan3 xin4: to text; to send SMS messages

Japanese common word / expression
赤信号 | あかしんごう akashingou: red light
青信号 | あおしんごう aoshingou: green light

*半信半疑 | はんしんはんぎ hanshin hangi
: half in doubt; half-convinced; dubious; incredulous

織田信長 [织田信长] zhi1 tian2 xin4 chang2 | おだのぶなが Oda Nobunaga
: Oda Nobunaga (1534-1582), Japanese shogun (warlord), played an important role in unifying Japan. After his murder, he was succeeded by Toyotomi Hideyoshi.

信じようと信じまいと | しんじようとしんじまいと shinjiyou to shinji maito
: believe it or not

Chinese idiom / proverb
*半信半疑 ban4 xin4 ban4 yi2: half-believe, half-doubt

無徵不信 [无征不信] wu2 zheng1 bu4 xin4
: without proof one can’t believe it

聽信謠言 [听信谣言] ting1 xin4 yao2 yan2
: to take heed of idle chatter

言而有信 yan2 er2 you3 xin4
: to speak and keep one’s promise; as good as one’s word

言而無[无]信 yan2 er2 wu2 xin4
: to go back on one’s word; to break one’s promise; to be unfaithful; to be untrustworthy

家醜不可外傳，流言切莫輕信 [家丑不可外传，流言切莫轻信] jia1 chou3 bu4 ke3 wai4 chuan2 , liu2 yan2 qie1 mo4 qing1 xin4
: Don’t spread abroad the shame of the family, don’t believe rumors lightly (common expression). Don’t wash your dirty linen in public, don’t listen to others’ gossip

言必信，行必果 yan2 bi4 xin4 , xing2 bi4 guo3
: one must be a man of his word and resolute in his work