Obsolete spelling of plat or plot (scheme, plan, design, map).
"The old mill was famous for weaving platt into sturdy bonnets that could withstand the harsh winter winds."
Obsolete spelling of plat (material made by interweaving, especially material made by interweaving straw, used to make hats).
Plattdeutsch, Low German
"The new neighbor, Mr. Platt, waved at us from his porch as he carried in a stack of firewood."
A village in Kent, England.
A surname.