Polysemy - Glossary Definition - UsingEnglish.com
Definition:
Polysemy refers to a word that has two or more similar meanings:
The house is at the foot of the mountains
One of his shoes felt too tight for his foot
'Foot' here refers to the bottom part of the mountains in the first sentence and the bottom part of the leg in the second.

The above is a source from www. Sassure and others assume English words are polysemous.
The above example , foot; is not really polysemous, for the basic meaning is "the bottom of something", as the source itself states. Other examples quote, 'you can bank on me' , 'the river bank' and the 'money in the bank' also have a basic meaning or function meaning 'that which is strong or reliable'.

While I accept words have cultural context and shades of meanings which deepen or change slightly, my understanding is words have a single basic meaning.

I asked an Italian once for a polysemous wordin Italian, and after some thought he came up with the word 'tree' and 'mast' on a boat. But I said, surely the mast on a boat looks like a tree and carries the same basic meaning. He agreed, and so there are really few polysemous words in any language.

What is everybody else's opinion out there ? Do words have a single basic meaning regardless of context?