What 𝄪 means
It raises a written note by two semitones.
That is one whole step. In equal-tempered tuning, F𝄪 sounds like G, but keeping the F spelling shows its place as the seventh step in G-sharp major.
Why write F double sharp instead of G?
The spelling keeps each scale step under its own letter.
Double accidentals entered notation as older church scale patterns gave way to major and minor keys; equal temperament later made a full cycle of keys practical. Historical notation books show a × form and cancellation with a natural followed by a sharp. A music textbook attributes a St Andrew’s cross proposal to Johann Mattheson.
Is 𝄪 an x?
It is the double-sharp sign; a typed x can be shorthand.
In plain-text music notation, x may stand in for the sign, but the characters differ: x is a keyboard letter, while 𝄪 is a dedicated music glyph.
Technical and exact: it marks written pitch in music notation.
Alone, it gives no pitch without a note or chord.
What it means when someone sends it to you
3 readingsDon't confuse it with
1Combination ideas
3Questions people ask
1Why does 𝄪 show as a box on some devices?
Because that device's fonts have no glyph for it. The character is still correct and still copies correctly — the box is a missing glyph, not a broken character.
How to type 𝄪
𝄪\1D12ACodes and encoding1 code points
A visible symbol can contain several code points. JS .length counts UTF-16 units; UTF-8 counts bytes.