From Proto-Tai *praːjꟲ (“to walk”).
byaij (Sawndip forms 𨃅 or 䠊 or 𬦱 or 派は or 𮛒 or 𰺺 or 跿 or 𨂐 or ⿺辶走 or ⿺走はし拜はい or 孨 or ⿰𧾷罢, 1957–1982 spelling byaiз)