Translation guide
The English phrase "first line" can refer to several distinct concepts. This guide helps learners choose the right Japanese expression based on the intended meaning, from literal lines of text to metaphorical front lines.
Referring to the very first line of a written work, such as a poem, letter, or paragraph.
The most common and neutral way to say 'first line' when talking about a line of text. 行 (ぎょう) means 'line' in a written context.
この詩の最初の行を読んでください。
Please read the first line of this poem.
手紙の最初の行に日付を書きます。
I write the date on the first line of a letter.
Literally 'the first line' using the counter 目 (め) for ordinal numbers. Very common in instructions or when referring to a specific line number.
一行目から三行目までを暗記してください。
Memorize from the first line to the third line.
A more literary expression meaning 'the opening line'. Often used when discussing the impactful first line of a novel or famous work.
この小説の冒頭の一行はとても有名です。
The first line of this novel is very famous.
Referring to the foremost position in a battle, competition, or effort, such as 'front line' or 'first line of defense'.
Means 'front line' or 'forefront'. Used in military contexts, but also metaphorically for being at the cutting edge of technology, research, or social movements.
彼はビジネスの最前線で活躍している。
He is active on the front lines of business.
医療従事者は常に最前線にいる。
Healthcare workers are always on the front line.
Simply 'front line' or 'front'. Can be used in military, weather (e.g., 前線 = weather front), or metaphorical contexts, but 最前線 is more common for 'forefront'.
Referring to the primary means of protection or the first step in a defensive strategy.
Direct translation of 'first line of defense'. Used in military, cybersecurity, and metaphorical contexts.
ファイアウォールは防御の第一線です。
The firewall is the first line of defense.
Another way to say 'first line of defense', slightly more literal. 防衛線 means 'defense line'.
免疫システムは体の最初の防衛線だ。
The immune system is the body's first line of defense.
Specifically referring to the opening lyrics of a song or the first verse of a poem.
Means 'the beginning of a song' or 'the first line of lyrics'. Very common when discussing music.
この曲の歌い出しが大好きです。
I love the first line of this song.
Means 'the first phrase'. Can be used for songs or poems, but 歌い出し is more specific to singing.
最初のフレーズを聞いただけで、何の曲かわかった。
Just by hearing the first line, I knew what song it was.
Referring to the first line of a street address or mailing address.
Means 'the first line of the address'. Used when filling out forms or explaining address formats.
住所の一行目には番地を書いてください。
Please write the street number on the first line of the address.
Generic 'first line', can be used for addresses as well, but adding 住所の makes it clearer.
最初の行に郵便番号を記入します。
Enter the postal code on the first line.
Referring to the initial line of code in a script or program.
Works for code as well. In programming contexts, 行 (ぎょう) is the standard term for 'line'.
このスクリプトの最初の行にエラーがあります。
There is an error in the first line of this script.
Also common when referring to line numbers in code.
一行目でインポート文を書きます。
Write the import statement on the first line.
When meaning 'front line' in a military or metaphorical sense, do not use 最初の線 (さいしょのせん). This sounds unnatural. Use 最前線 or 第一線 instead.
最前線 (さいぜんせん) emphasizes being at the very forefront, often with a sense of cutting-edge or extreme front. 第一線 (だいいっせん) is more about being in the main arena of activity, and is common in phrases like 第一線で活躍する. They overlap but 最前線 can sound more intense.
Literally 'first line'. Often used in phrases like 第一線で活躍する (to be active on the front lines) or 第一線を退く (to retire from the front lines). Common in professional contexts.
彼は長年、研究の第一線で働いてきた。
He has worked on the front lines of research for many years.
敵の前線を突破した。
We broke through the enemy's front line.