Negation and lack with

The kanji 不 functions as a marker of not, non-, and lack. In compounds it usually negates or reverses the meaning of the following element, creating words for absence, impossibility, defect, or insufficiency.

Limits and Inability

(Impossible)

不可能(ふかのう) means impossible or unable to be done.

It combines 不 (not) with 可能 (possible) to show the absence of possibility.

Example 1 of 2: Hidden behind the short hand with 短針
Example 1 of 2
Manga panel from 怪盗セイント・テール showing example of Hidden behind the short hand with 短針.
怪盗セイント・テール » Volume 1 » Page 54

Asuka Jr. is tasked with guarding a jeweled tiara, which Saint Tail has stated her intention to steal. The owner tells Asuka Jr. it’s been hidden behind the short hand on a clock tower, so Asuka Jr. waits below the face of the clock for Saint Tail’s arrival. He tells the owner that Saint Tail will likely arrive precisely at 6 o’clock.

アスカ Jr.:
「ここから短針(たんしん)に手(て)がとどくのは六(ろく)時(じ)だけです」
“The hour hand is only within reach from here at six o'clock.”
「ほかの時間(じかん)と針(はり)からティアラを盗(ぬす)みだすのは不可能(ふかのう)なんですよ」
“At any other time, it would be impossible to steal the tiara from the hand, you see.”
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Example 2 of 2: Indiscriminate murder would be one thing if with 〜ならともかく
Example 2 of 2
Manga panel from 名探偵コナン showing example of Indiscriminate murder would be one thing if with 〜ならともかく.
名探偵コナン » Volume 5 » Page 110

Sonoko is invited to a band’s after party. During the get-together, the band’s singer Tatsuya eats a rice ball only to collapse and die. The police are called in, and Inspector Megure discovers the victim was poisoned. He accuses the man who prepared the food, but Conan bites into a rice ball to show it’s safe. The victim’s manager, Mari, agrees.

麻理(まり):
「無差別(むさべつ)殺人(さつじん)ならともかく、たまたま達也(たつや)が食(た)べたオニギリだけに、あらかじめ毒(どく)を仕込(しこ)むのは不可能(ふかのう)じゃありません?」
“If it were indiscriminate murder, that's one thing but since it was just the rice ball Tatsuya happened to eat, wouldn't it be impossible to poison it beforehand?”
目暮(めぐれ):
「た、確(たし)かにそうだが…」
“Th-that's true.”
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Negative States

(Anxiety)

不安(ふあん) means anxiety or unease, often a vague fear that something may go wrong.

It combines 不 (not) with 安 (peaceful) to show a lack of ease.

Manga panel from ふらいんぐうぃっち showing example of When you're small with 〜うちは.
ふらいんぐうぃっち » Volume 5 » Page 49

During a visit with Anzu’s family, Makoto receives a request to babysit for another witch. Things are fine at first, but after a while, rain begins to pour inside. Anzu’s mother realizes that the child they’re watching over has rain magic.

杏子(あんず)の母(はは):
「小(ちい)さいうちはコントロールできないんだろうね。不安(ふあん)になると今(いま)みたいに降(ふ)らせちゃうんだね」
“You don't have control while you're small, right? When he's uneasy, it pours like just now.”
真琴(まこと):
「なるほど。そうですよね。いきなり知(し)らない所(ところ)じゃ心細(こころぼそ)いですよ。我慢(がまん)してたんですね」
“I see. So that's it. It's a little scary suddenly being in a place you don't know. You've been patient, haven't you?”
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(Defect)

不良(ふりょう) means defective or in poor condition. As a noun, it can mean a delinquent.

It combines 不 (not) with 良 (good) to show what is not good.

Manga panel from ふだつきのキョーコちゃん showing example of Thinking of revealing the truth with 〜ようと思う.
ふだつきのキョーコちゃん » Volume 3 » Page 167

Kenji thinks Kyouko is upset because he and Hikari don’t get along well.

ケンジ:
「オレは不良(ふりょう)のフリをしてるだけだってヒカリにバラそうと思(おも)うんだ!!」
“I think I will reveal to Hikari that I'm just pretending to be a delinquent!”
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(Misfortune)

不幸(ふこう) means misfortune, unhappiness, or an unfortunate circumstance.

It combines 不 (not) with 幸 (fortune) to show the absence of good fortune.

Manga panel from ご注文はうさぎですか? showing example of Better to give up fortune telling with 〜た+方がいい.
ご注文はうさぎですか? » Volume 1 » Page 100

Cocoa did fortune telling for her friends, only for all their fortunes to happen to her in a bad way.

チノ:
「ココアさんは人(ひと)の不幸(ふこう)の身代(みが)わりになる才能(さいのう)があるんですか?」
“Cocoa, do you have a talent for taking on other people's misfortune?”
リゼ:
「今後(こんご)占(うらな)いやめた方(ほう)がいいぞ自分(じぶん)のために」
“For your own sake, you had better stop fortune telling from now on.”
ココア:
「なんで!?」
“Why!?”
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(Unnatural)

不自然(ふしぜん) means unnatural, awkward, or contrived.

It combines 不 (not) with 自然 (natural) to show what is not natural.

Manga panel from 名探偵コナン showing example of Only the ace of spades with 〜だけ.
名探偵コナン » Volume 12 » Page 20

The Detective Boys group visits a cabin where Professor Agasa has secretly set out clues leading to a treasure. Conan draws the group’s attention to an arrow pointing to a table, on top of which there is…

コナン:
「これまた不自然(ふしぜん)に散(ち)らばったトランプの山(やま)…」
“A pile of cards, rather unnaturally scattered about.”
「しかも、なぜかスペードのAだけが画鋲(がびょう)でとめてある…」
“Further, for some reason, only the ace of spades is pinned down with thumbtacks...”
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States of Uncertainty

(Mystery)

不思議(ふしぎ) means mysterious, strange, or difficult to explain.

It combines 不 (not) with 思議 (ordinary reasoning) to show something beyond easy explanation.

Manga panel from 名探偵コナン showing example of It's not like this is science fiction with 〜じゃあるまいし.
名探偵コナン » Volume 3 » Page 147

Evidence piles up for Ran that Conan, the smart young boy staying with her family, may actually be Shin’ichi, her missing childhood friend. She’s convinced that he’s Shin’ichi on the inside, but the sticking point is how he went from being a teenager to a child.

欄(らん):
「SF(エスエフ)じゃあるまいし…」
“It's not like this is sci-fi.”
「こんな不思議(ふしぎ)な事(こと)ってありえない…」
“Such an incredible thing is inconceivable...”
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