一切|いっさいissai[1]atamadaka (head-high)

1. no-adjectiveall; everything; entirety; the whole
   それは他たのいっさいに勝かっている。↗

   It is paramount to all the others.
2. adverbabsolutely (not); (not) at all; (none) whatsoever; without exceptionwith neg. verb

• SynonymすべてNeutralThe most general word for 'everything/all'; 「一切」 stresses 'without exception' and often pairs with a negative for 'not at all'.
• SynonymまったくNeutralMeans 'completely, entirely' and can also be an exclamation ('good grief'); with a negative 「一切」 sounds stronger.
• Synonym全体ぜんたいNeutralPoints to the whole or the entire group, viewing things as one unit; 「一切」 stresses that nothing is left out.
• Synonym何もなにもNeutralWith a negative it means 'nothing, not anything'; 「一切」 is more written in flavor and more absolute.
• Synonym全部ぜんぶNeutralThe everyday word for 'all/everything', common in speech; 「一切」 leans written and stresses 'without exception'.
• SynonymみなNeutralCovers everyone or everything present, frequent in speech as in 「皆で行く」; 「一切」 is more written, stresses 'without exception', and can take a negative.
• SynonymすっかりNeutralMeans 'completely, entirely' and mostly appears in affirmative sentences like 「すっかり忘れた」; 「一切」 typically pairs with a negative.
• Synonym皆目かいもくWrittenWritten; with a negative it means 'not at all', as in the set phrase 「皆目見当がつかない」; its collocations are fairly fixed.
• SynonymまるっきりCasualColloquial; an emphatic form of 「丸きり」; 「一切」 is more written.
• Synonym少しもすこしもNeutralWith a negative it means 'not a bit'; 「一切」 puts more weight on 'without exception'.
• Synonym一向にいっこうにNeutralWith a negative it means 'not in the least', as in 「一向に構わない」; 「一切」 is more absolute.
• RelatedさっぱりCasualColloquial; with a negative it means 'not at all', as in 「さっぱり分からない」; 「一切」 is more written.
• RelatedちっともCasualColloquial; with a negative it means 'not in the least'; 「一切」 is more written.
• RelatedまんざらNeutralUsually in 「満更でもない」; it means 'not altogether', a partial negation pointing the opposite way from 「一切」's total 'not at all'.
• Related徹頭徹尾てっとうてつびWrittenA four-character idiom for staying consistent from start to finish; 「一切」 focuses on the totality of things.
• RelatedさらさらWrittenWritten style; with a negative it means 'not in the least', as in 「更々ない」; 「一切」 is far more common.
• RelatedまるきりCasualColloquial; means 'completely' and usually takes a negative; 「一切」 is more written.
• Antonym若干じゃっかんWrittenThe antonym on the all-versus-part axis: it means 'a few, a small amount, somewhat'.

Use 「一切」 for 'all without exception' or, with a negative, 'not at all, none whatsoever'; it leans toward written style. For 'everything/all' in everyday speech pick 「全部」 or 「全て」. For an emphatic 'not at all' in speech, 「全然」,「ちっとも」 and 「さっぱり」 are the natural choices, while 「皆目」 and 「更々」 do that job in writing. The opposite of 'all' is 「若干」.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

1. 除のぞくものなくすべてのもの。
2. すべてにおいて。
3. （否定ひてい表現ひょうげんに先行せんこうし、強つよい否定ひてい表現ひょうげんを作つくる）まったく、全然ぜんぜん（～ない）。