\usepackage[xetex,nomarginpar,margin=2cm,%showframe%
  ]{geometry}

\usepackage{ifthen}

\usepackage{tipa}
\usepackage{tipx}
\usepackage{fontspec}
\renewcommand\textipa[1]{{\fontfamily{cmr}\tipaencoding #1}}

\usepackage{pdflscape}
\usepackage{float}
\usepackage{caption}
\usepackage{tablefootnote}
\usepackage{makecell}
\renewcommand{\cellalign}{tc}
\renewcommand*{\thead}[1]{\multicolumn{1}{c}{#1}}
\usepackage{longtable,multicol,color}
\setlength{\columnsep}{2cm}
\newsavebox\ltmcbox

\usepackage[table]{xcolor}
\definecolor{lightgray}{gray}{0.98}

\let\oldlongtable\longtable
\let\endoldlongtable\endlongtable
\renewenvironment{longtable}{\rowcolors{2}{white}{lightgray}\oldlongtable} {\endoldlongtable}

\usepackage[pdfusetitle]{hyperref}
\hypersetup{
    bookmarksnumbered=true,
    bookmarksopen=true,
    bookmarksopenlevel=1,
    colorlinks=true,
    pdfstartview=Fit,
    pdfpagemode=UseOutlines,
    pdfpagelayout=TwoPageRight,
    linkcolor=blue,
    urlcolor=blue
}

% Activate as last:
\usepackage{polyglossia}
\setmainlanguage{italian}
\setotherlanguage{german}
\setotherlanguage[variant=american]{english}

\usepackage{lipsum}

\input{definitions}