broad in the beam

alternative broad across the beam · alternative broad-beamed

1. nauticalWide across the hull.

   Ah! She's not that old green launch with a yellow line, very broad in the beam?

   1890 February, A[rthur] Conan Doyle, “The Baker Street Irregulars”, in The Sign of Four (Standard Library), London: Spencer Blackett […], →OCLC, page 145

2. idiomaticespecially a femaleWide across the hips, with large buttocks.

   [T]he women of Falesa are a handsome lot to see. If they have a fault, they are a trifle broad in the beam.

   1905, Robert Louis Stevenson, chapter 1, in Island Nights' Entertainments