In TeXForm#
TeXForm parses this entry as a character leaf mapped to U+03C8 (GREEK SMALL LETTER PSI).
\bbalpha\bbbeta\bbchi\bbdelta\bbDelta\bbdotlessi\bbdotlessj\bbepsilon\bbeta\bbgamma\bbGamma\txtbbpsi
\txtbbpsiSymbol
The ψ symbol (Greek small letter psi, U+03C8), written as \txtbbpsi in LaTeX text mode.