長らく・永らく|ながらくnagaraku[2]nakadaka (mid-high)

1. adverblong; (for a) long time
   長ながらくお待またせして申し訳もうしわけありません。↗

   I'm sorry to have kept you waiting so long.

• Synonym長い間ながいあいだNeutralA very long time; common in everyday speech. 「長らく」 is a touch more formal and works in both greetings and plain narration.
• Synonym長々ながながNeutralSuggests something dragging on at length, as in 「長々と話す」; also used for lying stretched out. Often carries an impatient, negative nuance.
• Related末永くすえながくNeutralMeans forever, for many years to come, as in 「末永くお幸せに」; looks only to the future, never the past.
• AntonymしばらくNeutralUsually 'a while', but can also mean quite some time, as in 「しばらく会っていない」; the opposite of 「長らく」 when a short span is meant.
• Antonym暫時ざんじWrittenA brief moment or short while; written/formal prose, and the opposite of 「長らく」.

Use 「長らく」 for a long time with a slightly formal tone, as in 「長らくお待たせしました」 or 「長らく続く」. In casual speech say 「長い間」; for something drawn out, 「長々」; for lasting into the future, 「末永く」; for a short while, 「暫時」.

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

1. 長ながく。久ひさしく。長期間ちょうきかん。