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PlainSpell

underline

/ˈʌndɚˌlaɪn/noun, verb, adjective

underline is spelled U-N-D-E-R-L-I-N-E: 9 letters and 3 syllables. It appears about once in every 1 million words in written English, the 29,649th most frequent word form (wordfreq, 2021 data). As a noun, underline means “A line placed underneath a piece of text in order to provide emphasis or to indicate that it should be viewed in italics or (in electronic documents)…” (English Wiktionary, September 2026). The plural of underline is underlines.

How many letters and syllables are in underline?

Letters9: U-N-D-E-R-L-I-N-E
Syllables3 (from its American pronunciation)
In writingabout once in every 1 million words; the 29,649th most frequent word form
Wrong spellings searchednone measured in search

Sources: letters and syllables from the English Wiktionary's hyphenation or pronunciation and the CMU Pronouncing Dictionary; written frequency: wordfreq 3.1 (a 2021 snapshot of Wikipedia, subtitles, news, books, web text and social media).

How common is underline?

Underline appears about once in every 1 million words in written English, the 29,649th most frequent word form in the list.

Source: written frequency: wordfreq 3.1 (a 2021 snapshot of Wikipedia, subtitles, news, books, web text and social media).

How do you pronounce underline?

  • US /ˈʌndɚˌlaɪn/
  • UK /ˈʌndəˌlaɪn/
  • /ˌʌndɚˈlaɪn/

Underline has 3 syllables (counted from its American pronunciation in the CMU Pronouncing Dictionary).

Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract). Recordings: En-us-underline.ogg, Wikimedia Commons (author and licence on each file's page).

Forms of underline

  • underlines plural, present, singular, he/she/it
  • underlining participle, present
  • underlined participle, past

Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).

What does underline mean?

The meanings the English Wiktionary records, quoted as written there (source below).

noun

  1. 1

    A line placed underneath a piece of text in order to provide emphasis or to indicate that it should be viewed in italics or (in electronic documents) that it acts as a hyperlink.

  2. 2

    The character _.

  3. 3

    datedAn announcement of a theatrical performance to follow, placed in an advertisement for the current one.

  4. 4

    datedA caption beneath a photograph (which may have more than one line of text).

verb

  1. 1

    To draw a line underneath something, especially to add emphasis.

    underline the important words in the text

  2. 2

    To emphasise or stress something.

  3. 3

    obsoleteTo influence secretly.

adjective

  1. 1

    Passing under a railway line.

Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).

Underline in Spanish, French, German and Portuguese

LanguageWords
Frenchsoulignement (line underneath text), souligner (to draw an underline), attirer l’attention (to emphasise or stress something)
GermanUnterstreichung (line underneath text), unterstreichen (to draw an underline), Unterstrich (an _ character)
Portuguesesublinha (line underneath text), sublinhar (to draw an underline), underline (an _ character)
Spanishsubrayar (to draw an underline)

Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract). Translations are Wiktionary's, by sense; a linked word has its own PlainSpell page.

Where does underline come from?

From under- + line.

Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).

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