Denotation refers to the straightforward, dictionary meaning of a word without implying feelings or ideas. The denotation of 'snake' is simply a reptile, without the negative connotations some people associate with it.
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Multiple Meanings
Some words have more than one denotation, so context determines the correct meaning. Depending on context, 'bark' can have the denotation relating to a tree or a dog's sound.
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Cultural Variations
The denotation of words can change across cultures, even if the language is the same. In British English, 'biscuit' has the denotation of what Americans would call a 'cookie'.