lumpiest

Lumpiest is the superlative form of lumpy, describing something with the most lumps or irregular bumps compared to others.

It typically characterizes textures that should be smooth but aren't—gravy, mattresses, pillows, or poorly mixed batter.

This is the lumpiest oatmeal I've ever tried to eat.

The word can also describe uneven terrain or, figuratively, a particularly rough or difficult situation.