O in Morse Code: −−−
The letter O in Morse code is −−−, spoken as "DAH-DAH-DAH": three long. That is 3 dashes, with a dash held three times as long as a dot. To remember it, think OH MY GOSH (three long beats).
Timing: how long each part lasts
Morse timing is built from one unit, the length of a dot. A dash is 3 units, and the silence between the elements of a single character is 1 unit. At 20 words per minute, one unit is 60 ms, so O breaks down like this:
| Element | Signal | Length (units) | At 20 WPM |
|---|---|---|---|
| Dash | − | 3 | 180 ms |
| Gap | (silence) | 1 | 60 ms |
| Dash | − | 3 | 180 ms |
| Gap | (silence) | 1 | 60 ms |
| Dash | − | 3 | 180 ms |
| Total for O | 11 | 660 ms | |
How to signal O
- Tap it: three long. A short is a quick tap; a long is a heavier tap, or a quick tap followed by a slight hold, about three times as long.
- Blink it: three long. Use quick blinks for dots and slow, deliberate eye closes for dashes, keeping the rhythm steady.
- Flash it: three long. Short flashes for dots; for dashes, hold the light on about three times longer. Any flashlight or phone screen works.
How to remember O
Say OH MY GOSH (three long beats) in rhythm with the code and the pattern sticks: "DAH-DAH-DAH".
Words that start with O: Oscar −−− ··· −·−· ·− ·−·, oak −−− ·− −·−, ocean −−− −·−· · ·− −·, orbit −−− ·−· −··· ·· −. The first is O's NATO phonetic name, which operators use to spell aloud.
O is one of the most common letters in English yet carries one of the most expensive codes, three full dashes. It is a known quirk of the original letter-frequency estimates, and it forms the middle of SOS.