# Undefined control sequence, extra \fi and overfull \hbox errors

I am using the code below to add the list of symbols to my document. I am getting the following errors for the rows where the function \ifthenelse is used:

1. Undefined control sequence for all of them
2. Extra \fi only for the first 2 (so for the \addchap{List of Symbols part and the one with symbol)
3. Overfull \hbox for the one with the symbol
% Symbolverzeichnis
$a$ & \ifthenelse{\boolean{english}}{acceleration}{Beschleunigung} & $\unit{\frac{m}{s^2}}$\\
$F$ & \ifthenelse{\boolean{english}}{force}{Kraft} & $\unit{N}$

• Overfull \hbox just refers a line that LaTeX had some trouble setting to its liking. Unless the line visually looks bad, there's usually no need to make any changes. Jun 16 at 22:11