broad, wide

Both these words have the same antonym, narrow, a clear indication they are similar in meaning. Wide refers to the distance that separates the limits, and broad to the amplitude of what connects them. Backs, smiles and shoulders can be broad, but mouths are wide.

• This glass jar has a wide mouth, which makes it easy to get the pickles out.
• My bookcase is 140 cm high, 90 cm wide and 35 cm deep.
• Weightlifting will give you a broad back.
• Nassim was wearing a broad grin as she came down from the stage.

Note that wide is sometimes used to qualify “shoulders” when emphasizing the distance from one side to the other, rather than the density, size and thickness of the shoulders, i.e. the broadness.

• Swimmers often have wide shoulders, whereas football linebackers tend to be broad-shouldered.