A key that produces no output immediately but modifies the next keystroke. Used for diacritics: pressing ` then e produces è. Common on European keyboard layouts.

Dead Key — Unicode Glossary

What is a Dead Key?

A dead key is a keyboard key that does not produce a character immediately when pressed — instead, it waits for the next keystroke and combines the two inputs to produce a modified character. The key is "dead" because pressing it alone produces nothing visible; it only comes alive when followed by a compatible base character.

Dead keys are the primary mechanism for typing accented characters on keyboards that don't have dedicated keys for every diacritic combination. They are ubiquitous on European keyboard layouts: the French AZERTY keyboard has dead keys for ^ and ¨, the German QWERTZ keyboard has dead keys for ^ and ´, and many others.

How Dead Keys Work

Press the dead key (e.g., the key labeled ´ acute accent)
The cursor shows nothing (or a placeholder like ´ underlined in some implementations)
Press a base character (e.g., e)
The combined character is output (é)

If the combination is not defined, most systems either output both characters separately (´ then e) or just the dead key's nominal character.

Common Dead Keys and Their Combinations

Dead Key	Name	+ a	+ e	+ i	+ o	+ u
´	Acute	á	é	í	ó	ú
`	Grave	à	è	ì	ò	ù
^	Circumflex	â	ê	î	ô	û
¨	Diaeresis	ä	ë	ï	ö	ü
~	Tilde	ã	—	—	õ	—
°	Ring	å	—	—	—	ů
ˇ	Caron	ǎ	ě	ǐ	ǒ	ǔ
¸	Cedilla	—	ę	—	—	—

To type the dead key's character alone (e.g., just an acute ´ as a standalone diacritic), press the dead key followed by Space. This produces the standalone combining or spacing diacritic.

Dead Keys on macOS

macOS uses the Option key as a dead key modifier in the US keyboard layout:

Option + key	Result (then type base)
Option + e	◌́ Acute accent
Option + `	◌̀ Grave accent
Option + i	◌̂ Circumflex
Option + u	◌̈ Diaeresis/Umlaut
Option + n	◌̃ Tilde

So: Option + e, then e = é. Option + u, then u = ü. The long-press character popover (introduced in macOS Lion) provides an even simpler alternative.

Dead Keys vs. Compose Keys

Feature	Dead Key	Compose Key
Mechanism	Hold to modify next key	Prefix key then sequence
Simultaneity	Key held during next press	Sequential, no holding
OS integration	Built into keyboard layouts	Separate key designation
Flexibility	Fixed to keyboard layout	Highly customizable
Typical platform	European keyboards, macOS Option	Linux X11, WinCompose

Unicode Encoding

Dead key combinations produce precomposed Unicode characters (e.g., é = U+00E9), not a base character followed by a combining mark. The IME/keyboard driver performs this composition and outputs the single code point. If no precomposed form exists, some systems fall back to the base + combining mark representation.

Quick Facts

Property	Value
Definition	Key that modifies the next keystroke to produce a diacritic
Visual feedback	Nothing displayed until base character pressed
Dead key alone	Press dead key + Space → outputs standalone diacritic
macOS acute dead key	Option + E, then base letter
macOS umlaut dead key	Option + U, then base letter
Difference from Compose	Dead key is held/pressed before; Compose is a prefix latch
Output format	Usually precomposed Unicode (single code point)
Keyboard layouts with dead keys	French AZERTY, German QWERTZ, Spanish, Portuguese, Nordic

Dead Key