年中|ねんじゅうnenjuu[1]atamadaka (head-high)

1. nounwhole year; all year round; throughout the year
   私は１年ねん中ちゅうテニスをします。↗

   I play tennis all the year around.
2. adverbalways; all the time; perpetually
3. nounduring an era
4. nounsecond-year kindergarten student

• Synonym年間ねんかんNeutralNeutral. A span of one year, as in 「年間計画」; states duration objectively, with no sense of 'all the time'.
• SynonymしょっちゅうCasualColloquial. Often, time and again; stresses frequency rather than a year-long span.
• SynonymいつもNeutralColloquial. 'Always; usually' — the most commonly used of the group.
• Synonym四六時中しろくじちゅうNeutralNeutral. Around the clock, nonstop; often hyperbolic or with a negative shade.
• Synonym常につねにNeutralWritten/formal prose. 'At all times'; leans formal.
• Synonym絶えずたえずNeutralRather written/formal; means without interruption, stressing unbroken continuity.
• SynonymいつでもNeutralNeutral. At any time, always; also 'whenever you like', as in 「いつでもどうぞ」. Unlike 「年中」, it does not stress the whole year.
• Synonym常々つねづねWrittenWritten/formal prose. 'As a rule; habitually', mostly about one's own thoughts or feelings.
• Synonym年がら年中ねんがらねんじゅうCasualColloquial; stronger than 「年中」. Covers all year round, day in and day out, often with a complaining tone.
• Synonym年百年中ねんびゃくねんじゅうCasualColloquial; synonymous with 「年がら年中」 but rarely used.
• Related一年いちねんNeutralNeutral. Simply the length of one year; objective, with no nuance of constant, year-round occurrence.
• Related明け暮れあけくれWrittenWritten/formal prose. From morning till evening; in 「～に明け暮れる」 it means spending one's days absorbed in something.
• Related始終しじゅうNeutralNeutral. From start to finish, or constantly, as in 「始終しゃべっている」; not limited to a year — applies within some period.
• Related常つねNeutralNeutral. The usual state of things, as in 「世の常」; a noun, not used adverbially to mean all year round.
• Related日夕にっせきWrittenWritten/formal prose for day and night; almost never used in modern Japanese.
• Related常住坐臥じょうじゅうざがWrittenWritten/formal prose. A four-character idiom for daily life, sitting or lying; not used in everyday speech.
• AntonymひとときNeutralNeutral. A moment, a short while — the opposite of the year-round 「年中」.

For the whole year or all year round, use 「年中」, as in 「年中無休」. For emphatic colloquial 'all year round' say 「年がら年中」; for 'always' 「いつも」; for 'frequently' 「しょっちゅう」; for an objective one-year span 「年間」. The opposite of 「年中」 is 「ひと時」, a moment.

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

1. 一いち年ねんの間あいだ。
2. （ねんじゅう）（副詞ふくし的てき）終始しゅうし。たえず。
3. （ねんちゅう）幼稚園ようちえんなどで、上うえから二に番目ばんめの学年がくねん。