documentclass{article}

usepackage[nonumberlist]{glossaries}
makeglossaries
newglossaryentry{Hull}{name=Hull,description={Canoe body.}}
newglossaryentry{Main sail}{name={Main sail},description={Hoistable, foldable cloth}}
newglossarystyle{mylong}{%
setglossarystyle{long}%
renewcommand*{glstextformat}{textbf}
renewenvironment{theglossary}%
{begin{longtable}[l]{@{}p{dimexpr 3.5cm-tabcolsep}p{0.8hsize}}}% <-- change the value here
    {end{longtable}}%
renewcommand{glsgroupskip}{}
}

usepackage{titlesec}
usepackage{fontspec}
defaultfontfeatures{Ligatures=TeX}
setmainfont[
Ligatures=TeX,
ItalicFont={z_CALIBRILI.TTF},
BoldFont={z_CALIBRI.TTF}
]{z_CALIBRIL.TTF}

newfontfamilysectionfont{z_CAMBRIAI.TTF}
titleformat*{section}{Largesectionfont}

usepackage{booktabs}
usepackage{tabularx}
usepackage{subfiles}

% enumitem package allows list items to be prepended with section number: nice
% it also controls the format of the section numbers / letters
usepackage{enumitem}

usepackage{gensymb}
setenumerate[1]{label=thesection.arabic*,labelsep*=12pt}
setenumerate[2]{label=(alph*)}

begin{document}

section{Example Section}
begin{enumerate}
item The boat shall have:
begin{enumerate}
    item One hull,
    item One mast, and
    item One main sail.
end{enumerate}
item The boat shall be no longer than 75 feet.
end{enumerate}
glsaddall
printglossary[style=mylong,title=Definition,toctitle=Notation]

end{document}