Unicode: 00B8. Alias: Esc cd Esc. Letter-like form. Used in an underscript position as a diacritical mark.
Unicode: 22EF. Letter-like form. Used to indicate omitted elements in a row of a matrix.
Unicode: 2232. Alias: Esc ccint Esc. Compound operator. ∲ f x is by default interpreted as ClockwiseContourIntegral[f,x].
Unicode: 2318. Alias: Esc cl Esc. Letter-like form. Used on Macintosh and other computers to indicate command keys.
Unicode: 222E. Alias: Esc cint Esc. Compound operator. ∮ f x is by default interpreted as ContourIntegral[f,x].
Unicode: F763. Alias: Esc ctrl Esc. Letter-like form. Representation of the Ctrl key on a keyboard.
\[Cup]
(Mathematica Character Name) Unicode: 2323. Infix operator. x ⌣ y is by default interpreted as Cup[x,y]. Used in pure mathematics to mean cup product.
Unicode: 03D2. Aliases: Esc cU Esc, Esc cUpsilon Esc. Greek letter. Not commonly used. Used in astronomy for mass to light ratio.
Unicode: 03F0. Aliases: Esc ck Esc, Esc ckappa Esc. Greek letter.
Unicode: 03D6. Aliases: Esc cp Esc, Esc cpi Esc. Greek letter. Not commonly used, except in astronomy.