四六時中|しろくじちゅうshirokujichuu[0]heiban (flat)

1. adverb, nounaround the clock; day and nightbecause 4 x 6 = 24
   ３人にんの看護婦かんごふが四六よんろく時じ中ちゅう瀕死ひんしの大臣だいじんの看護かんごに当あたった。↗

   Three nurses attended the dying minister night and day.

• SynonymいつでもNeutralAt any time, whenever — stresses that something is available whenever needed; 「四六時中」 stresses that something goes on all day long.
• Synonym絶えずたえずWrittenContinuously without interruption; mainly written/formal prose, stressing that there is no letup.
• Synonym常につねにWrittenAlways, constantly; standard in written/formal prose, and lacks the all-day-long exaggeration of 「四六時中」.
• SynonymいつもNeutralThe everyday default: usually, always; it does not stress unbroken continuity through time.
• Synonym明け暮れあけくれNeutralFrom morning to night, day after day; usually in the pattern 「…に明け暮れる」, spending one's days absorbed in something.
• Synonym年中ねんじゅうNeutralThe whole year; as an adverb, all the time, common in speech — a span longer than a single day.
• Synonym朝夕あさゆうNeutralMorning and evening, extended to constantly; mostly seen in written prose, as in 「朝夕の冷え込み」.
• Synonym始終しじゅうNeutralFrom start to finish, throughout; also all the time, as in 「始終笑っていた」.
• SynonymしょっちゅうCasualColloquial: often, all the time; stresses frequent repetition rather than continuous, unbroken duration.
• Synonym年がら年中ねんがらねんじゅうCasualColloquial, all year round; often carries a complaining tone, and spans a whole year rather than a single day.
• Synonym日夕にっせきWrittenDay and night, or nightfall; a rarely used written Sino-Japanese word.
• Synonym年百年中ねんびゃくねんじゅうCasualAll year round; a rarely used variant of 「年がら年中」.
• Synonym常住坐臥じょうじゅうざがWrittenA four-character phrase of Buddhist origin: in all one's daily activity, at every moment; written/formal.
• Synonym夜昼よるひるNeutralDay and night; colloquial and rather dated, as in 「夜昼なく働く」.
• Synonym常住じょうじゅうWrittenMostly permanence, something unchanging, or permanent residence; rarely used to mean always.
• Synonym明けても暮れてもあけてもくれてもNeutralIdiom for doing the same thing day in, day out, often with a weary, fed-up tone.
• Synonym間断なくかんだんなくWrittenUnbroken, without a single gap; written/formal, mostly describing actions or states that continue without pause.
• SynonymのべつCasualColloquial: nonstop, one thing after another; often as 「のべつ幕なし」, for talking, eating and the like.
• Related常々つねづねNeutralOrdinarily, all along; often used for something one has long kept in mind, as in 「常々思っている」.
• Related常つねWrittenA noun for the usual state or the way of the world, as in 「世の常」; not used adverbially for all day long.
• RelatedずっとCasualThe most common colloquial choice: continuously, the whole time; also far more, by far, for degree.
• Related決まってきまってNeutralInvariably, without fail whenever a given situation arises; stresses regularity, not unbroken duration.
• Related毎々まいまいWrittenEach time, every time; mostly in written letters of thanks, as in 「毎々お世話になり」.
• AntonymひとときNeutralAntonym: a short while, a brief period — the opposite of 「四六時中」's all-day nonstop sense.
• Antonym一瞬いっしゅんNeutralAntonym: an instant, a split second — the opposite of 「四六時中」's day-and-night continuity.

In everyday conversation, 「いつも」 and 「ずっと」 are the go-to words, and 「しょっちゅう」 for things that happen frequently. 「四六時中」 itself means all day long, nonstop, with a deliberately exaggerated feel. In written or formal prose, the standard choices are 「常に」 and 「絶えず」.

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

1. 一いち日にち中ちゅう。
2. ずっと、いつでも、しょっちゅう。