Underscore in Morse code
Written “_”, not in the ITU standard
The underscore (_) is usually sent in Morse code as ..--.-, said di-di-dah-dah-di-dah, the letters U and K run together. It is unofficial: ITU-R M.1677-1 has no underscore. Charts, amateur lists and translators use this code so text such as user names can be sent, but a listening operator may not know it.
..--.- (dot dot dash dash dot dash)
“di-di-dah-dah-di-dah”dot dot dash dash dot dash
6 elements · 3 dots, 3 dashes · 17 units
Hear it at your speed (WPM)
1133 ms at 18 WPM
The underscore at a glance
- Morse code
- ..--.-
- Said as
- di-di-dah-dah-di-dah
- Elements
- 6
- Length
- 17 units
- At 18 WPM
- 1133 ms
- ITU standard
- No
- Sounds like
- UKLetters run together
Not an ITU sign
ITU-R M.1677-1 has no underscore. Wikipedia lists ..--.- among nonstandard punctuation, and K3WWP's amateur list gives the same code under the name underline. This site's Morse code translator uses it too, so MY_NAME, the text in this page's practice box, translates and decodes here.
What it means in a message
In computer text the underscore joins words without a space, as in a user name or a file name.
Wikipedia also describes an informal habit of underlining a word by sending the sign before and after it, as in _MORSE_, but marks that claim as needing a source, so treat it as a convention to agree on first.
The question mark with a dash
Change the final dot of the question mark, ..--.., to a dash and you have the underscore, so the last sound is all that separates them. It takes 17 units, about 1.13 seconds at 18 WPM.
- The close bracket,
-.--.-, differs only in its first element. - The digit 2,
..---, shares its first four elements. - With a normal letter gap,
..- -.-is two letters, U and K.
Hear it
- ?..--..
- )-.--.-
- 2..---
Characters to compare
Close to the underscore in sound, so the likeliest mix-ups.
- Underscore with its 1st dot as a dash: Close bracket, dash dot dash dash dot dash
- Underscore with its 6th dash as a dot: Question mark, dot dot dash dash dot dot
- The first half: U, dot dot dash
Which one did you hear?
Listen, then pick or type the one you heard.
Try the underscore in a word
Tap the underscore yourself
Press for a dot, hold for a dash. Space works too.
- Send
- ..--.-
- Yours
- Nothing yet
Questions about Underscore.
What does _ mean in Morse code?
As a character, _ is the underscore, sent in unofficial charts as ..--.-, the letters U and K run together. It is not part of the ITU standard and has no procedural meaning on the air.
What is dot dot dot dash in Morse code?
Dot dot dot dash, ...-, is the letter V. The underscore has only two dots before its dashes, so count them: three dots then a dash is V.
Will every operator know the underscore?
No. Because it is not in the standard, a receiver may not recognize it. If it matters, spell out UNDERSCORE or agree on the sign before you send.
How is SOS sent in Morse code?
SOS is ...---..., three dots, three dashes and three dots sent as one signal. The SOS page plays it and explains its timing.