1. Synonymy: This refers to the relationship between words that have the same or nearly the same meaning. For example, "happy" and "joyful" are synonyms.
2. Substitution: This is a broader concept that refers to the replacement of one element of a sentence with another. It can involve synonyms, but also other grammatical categories like pronouns, determiners, or even entire phrases.
3. Equivalence: This focuses on the idea that different expressions can have the same meaning or function in a sentence. It's often used in relation to paraphrasing or translation.
4. Lexical ambiguity: This refers to situations where a single word can have multiple meanings. In some cases, these different meanings might lead to the same answer depending on the context.
5. Idioms and figurative language: Some expressions have a meaning that is not directly derived from the individual words. These can sometimes be replaced with other idioms or figurative language that convey the same meaning.
Example:
"The dog chased the ball."
This sentence could be rewritten as:
"The canine pursued the spherical object."
While the words are different, the meaning remains the same. This is an example of substitution using synonyms and perhaps some lexical ambiguity.
It's important to remember that the specific term will depend on the specific situation and how the words are being used.