is an attribute that, once assigned, prevents modification of any attributes of a symbol.


Locked
is an attribute that, once assigned, prevents modification of any attributes of a symbol.
Examples
open all close allProperties & Relations (5)
The attribute Locked, once set, cannot be removed:

By itself, the attribute Locked does not prevent adding definitions to a symbol:
However, no new attributes can be added:

If a symbol is protected and locked, its definitions can no longer be changed:


Clear can clear the values and definitions for locked symbols:
ClearAll does not affect locked symbols:

Remove does not affected locked symbols:

Tech Notes
Related Guides
History
Introduced in 1988 (1.0)
Text
Wolfram Research (1988), Locked, Wolfram Language function, https://reference.wolfram.com/language/ref/Locked.html.
CMS
Wolfram Language. 1988. "Locked." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/Locked.html.
APA
Wolfram Language. (1988). Locked. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/Locked.html
BibTeX
@misc{reference.wolfram_2025_locked, author="Wolfram Research", title="{Locked}", year="1988", howpublished="\url{https://reference.wolfram.com/language/ref/Locked.html}", note=[Accessed: 11-August-2025]}
BibLaTeX
@online{reference.wolfram_2025_locked, organization={Wolfram Research}, title={Locked}, year={1988}, url={https://reference.wolfram.com/language/ref/Locked.html}, note=[Accessed: 11-August-2025]}